JPS60210504A - Reforming apparatus - Google Patents

Abstract

PURPOSE:To make the temp. of tube walls unform and to reform with high efficiency by measuring the temp. of each reformer tube, and regulating the supply of the combustion gas and the inflow rate of the gas to be reformed from the mean temp., control temp., and measured temps. in the heating-system reforming apparatus. CONSTITUTION:Combustion gas and air are supplied from a combustion gas line 21 and a combustion air line 22 into a combustion chamber 3, and burned to heat each reformer tube 6. The wall temp. of the reformer tube 6 is measured with each temp. measuring element 15, and the mean temp. is obtained. The opening degree of each regulating valve 27 provided to a reformed gas line 26 is respectively controlled so that the deviation between each measured temp. may be nullified to regulate the inflow rate of the gas to be reformed to the reformer tube 6. Besides, the mean temp. is compared with the preset limit temp., and the opening degree of a combustion gas regulating valve 23 provided to the combustion gas line 21 is controlled to regulate the inflow rate of the combustion gas to the reformer tube 6 so that the deviation may be nullified.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is an improvement of a heated gas reformer in which reformed gas passes through a plurality of reforming tubes, and heating gas flows outside the tubes to heat them simultaneously. It is related to.

[Technical background of the invention]

The configuration of this type of gas reformer that is commonly used will be explained using the cross-sectional view shown in FIG. In the figure, a reformer 1 sends combustion gas and combustion air to a burner 2, combusts it in a combustion chamber 3, and directs the heated fluid generated by this combustion to an exhaust gas outlet 5 through a heating channel. Discharge outside. This combustion heat heats a plurality of reforming tubes 6 each having an annular cross section provided inside the reforming device 1.

Inside the reforming tube 6, a reformed gas flow path is provided completely separated from the combustion gas heating flow path 4. The reformed gas flowing in from the lower part of the reformed gas flows up inside the catalyst layer 8 provided on the inner wall of the reforming tube 6 and supported by a lower perforated plate, and changes direction in the opposite direction at the upper end. The reformed gas flows through a return path 10 formed between the catalyst layer 8 and the center lag 9, and exits from the reformed gas outlet 11. If reformed gas is fed during this time, methane and water vapor will be reformed into hydrogen and carbon dioxide gas. In some cases, only one reforming pipe 6 is provided inside the reforming device 1, but in general, a plurality of reforming pipes 6 are provided inside the reforming device 1, as shown in FIG.

[Problems with background technology]

By the way, in the above-mentioned reformer, when a plurality of reformer tubes 6 are provided in one reformer 1, there is a problem that the tube wall temperature of the reformer tubes 6 becomes non-uniform. This point will be described below using FIG. 2. FIG. 2 shows the cross-sectional structure of the upper part of the reforming tube 6. In the figure, the reforming tube 6 is made by welding an end plate 12 and a weld line 13.

Since the upper portion of the reforming tube 6 near the combustion chamber 3 reaches a high temperature as already described in FIG. 1, a cap 14 made of a heat insulating material is placed over the end plate 12. Also,
Since defects are likely to occur in the weld line 13, a temperature measuring element 15 is provided at this portion to measure the temperature. The reformed gas rises in the catalyst layer 8, passes through the catalyst upper end 16, reverses itself above the perforated plate 17, and descends through the return path 10 formed by the plug guide 19 to flow out. Note that 20 indicates a catalyst layer inner tube.

Now, as a result of actually manufacturing a single reformer with a plurality of reforming tubes 6, and conducting an experiment by installing a temperature measuring element 15 on the wall of each reforming tube 6, we found that It has become clear that the tube wall temperature is not uniform for each tube 6 and that a large temperature difference occurs. In other words, the operating temperature of the reforming tube 6 has a large effect on the failure life of the reforming tube 6, and the operating temperature is 1.
The 10-year lifespan will be shortened by about 3 years due to the 0°C increase in temperature. Therefore, if there is non-uniformity in temperature among the reforming tubes 6, looking at the highest temperature among the non-uniform temperatures,
The reformer must be operated while adjusting the amount of combustion gas supplied to the burner 2 so that this maximum temperature becomes the limit temperature. However, in this case, the reforming efficiency deteriorates in the reforming tube 6 having the lowest temperature.

As mentioned above, the conventional reformer has the following problems.

If the tube wall temperature is uneven, the life of the high-temperature reforming tube 6 will be short, and the low-temperature reforming tube 6 will have poor reforming efficiency of the reformed gas, for example, converting methane and steam into hydrogen and carbonic acid. When reforming into gas, the amount of residual methane increases as the width of temperature non-uniformity increases. In other words, if the operation is performed with the average tube wall temperature of a plurality of reforming tubes 6 adjusted to the limit temperature, the high-temperature reforming tubes 6 will have a short lifespan and will be damaged quickly. Reforming tubes with a low temperature have poor reforming efficiency, and the more there are reforming tubes 6 with low temperatures, and the lower their temperatures are compared to the average temperature, the greater the amount of methane that is not reformed.
The overall reforming efficiency of the reformer will decrease.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned problems, and its purpose is to uniformize the tube wall temperature of each reforming tube in a structure with a plurality of reforming tubes, thereby increasing the lifespan. Another object of the present invention is to provide a reforming device that can carry out reforming with high efficiency.

[Summary of the invention]

In order to achieve the above object, the present invention includes a plurality of reforming tubes each having an annular cross section, one end of which is sealed, and a reforming catalyst layer is provided between an inner pipe line and an outer pipe line. The combustion gas and the heated fluid obtained by burning the combustion gas in the combustion chamber are discharged from one end of the reforming tube through the outside thereof, and the reformed gas is discharged from the other end of the reforming tube. In a reformer configured to allow the fuel to flow in through the reforming catalyst layer from one end to the other end, and to flow out from the other end through the inner pipe line, the combustion gas is provided on a combustion gas line that supplies the combustion gas. A combustion gas control valve, a reformed gas control valve provided on each of a plurality of reformed gas lines for individually flowing the reformed gas into each of the reforming tubes, and a pipe wall temperature of each of the reforming tubes. Compare the average temperature of the temperature measured by each temperature measuring element and a predetermined limit temperature, and set the temperature to zero based on the comparison result. a first valve controller that controls the opening degree of the combustion gas regulating valve to adjust the temperature; and a first valve controller that separately compares the average temperature with the temperature measured by each temperature measuring element, and adjusts the reforming temperature based on the comparison result. The present invention is characterized in that it comprises a tube wall temperature control circuit including a second valve controller that separately controls the opening degree of the corresponding reformed gas control valve in order to adjust the inflow amount of gas.

[Embodiments of the invention]

First, in the present invention, the reason why the tube wall temperature of the reforming tube becomes uneven is that
One possible cause is that the combustion heating fluid becomes non-uniform around the reforming tube, but another reason is that the reforming gas flowing inside the reforming tube undergoes an endothermic reaction, resulting in an increase in the amount of inflow of this gas. Heterogeneity is also considered to be one of the causes, and we are particularly trying to deal with the latter cause.

An embodiment of the present invention shown in the drawings will be described below.

FIG. 3 is a cross-sectional view showing a schematic configuration of the reformer according to the present invention, and the same parts as in FIGS. Now, I will only discuss the different parts. In this example, the number of reforming tubes 6 is three.

In the figure, 21 and 22 are a combustion gas line and a combustion air line for supplying combustion gas and combustion air to the burner 2, respectively, and 23 and 24 are provided on the combustion gas line 2 and the combustion air line 22, respectively. These are a combustion gas control valve and a combustion air control valve. On the other hand, 2
Reference numeral 5 denotes three reformed gas pipes 2 provided to supply the reformed gas flowing from the reformed gas lower part into the reforming pipe 6 and to each of the lower chambers 26 and the lower part of the reformed gas pipe. Reference numeral 27 indicates a reformed gas control valve provided on each reformed gas line 26. Further, 28 is a reformed gas discharge control valve provided at the reformed gas outlet 11, the opening degree of which is automatically adjusted according to the load capacity of, for example, a fuel cell. . Furthermore, 29 is a sleeve pipe arranged concentrically on the outer circumferential side of each of the reforming pipes 6, and 15 is a sleeve pipe disposed concentrically with each of the reforming pipes 6.
A temperature measuring element is installed on the upper end of the tube wall to measure the tube wall temperature, and the measured temperature of L is T1 + T2 + T, respectively.
It is output as s.

FIG. 4 is a block diagram showing an example of a tube wall temperature control circuit applied to the present invention. In the figure, 30 indicates the temperature 'r1t T29 measured by each temperature measuring element 15.
an average temperature calculator 31 which calculates the average temperature TA of T's;
A first valve controller inputs the average temperature TA from 0, and sends a valve opening control signal to adjust the flow rate of the combustion gas so that the deviation between each temperature Ta and TA becomes zero. This is provided to the combustion gas control valve 23 mentioned above.

Reference numeral 32 denotes a second valve controller provided corresponding to each of the reforming pipes 6, which receives the average temperature TA from the average temperature calculator 30 and the temperature T measured by each temperature measuring element 15.
I and TffitT8 are compared individually, and a valve opening control signal is given to the reformed gas control valve 27 corresponding to the husband and husband in order to adjust the inflow amount of the reformed gas so that the deviation becomes zero. It is something.

Next, the operation of the reformer having such a configuration will be explained.

In the figure, the combustion gas and combustion air are fed into the burner 2 through the combustion gas 2-in 21 and the combustion air 2-in 22, and are combusted in the combustion chamber 3 as described above, thereby causing The heated fluid passes through the heating flow path 4 and is discharged to the outside through the exhaust gas outlet 5. On the other hand, the reformed gas flowing from the lower part of the reformed gas passes through the reformed gas line 25 provided for each husband and wife into the lower chamber 26 of each reforming pipe 6.
It then flows inside the catalyst layer 8 of the reforming tube 6, rises, changes direction in the opposite direction at the upper end, and flows into the return i4 space 10 formed between the catalyst layer 8 and the center plug 9. The reformed gas flows out through the reformed gas outlet 11. During this time, reformed gas such as methane and steam is reformed into hydrogen and carbon dioxide in each reforming tube 6.

On the other hand, since the reforming reaction is an endothermic reaction as described above, heat is generated in each reforming tube 6 due to the reaction, and the temperature of the wall of the reforming tube 6 increases.

Then, the tube wall temperature Tl l'r21' of each reforming tube 6
r3 is measured by the temperature measuring elements 16 provided respectively. Furthermore, the average temperature calculator 30 calculates the average temperature TA of these measured temperatures 'rl, 'r2t'r. Next, the second valve controller 32 compares each of the measured temperatures Tl#'r, +TB with the average temperature TA, and determines the respective temperatures T.

The valve opening degree of each reformed gas control valve 27 provided in each reformed gas line 25 is individually controlled so that the deviation between T2, TA s'rs, and TA becomes zero. In this case, the amount of reformed gas flowing into the reforming tubes 6 is adjusted to maintain the tube wall temperature of each reforming tube 6 at the average temperature TA. moreover,
The first valve controller 31 compares the average temperature T of each of the reforming pipes 6 with a preset limit temperature T, and adjusts the average temperature T of each of the reforming pipes 6 so that the deviation between each temperature Ts and TA becomes zero. By controlling the opening degree of the combustion gas control valve 23 provided in the combustion gas line 21, the amount of combustion gas flowing into the reforming tube 6 is adjusted, and the tube wall temperature of each reforming tube 6 is adjusted. The temperature limit will be maintained at T8.

Now, in the above, if the inflow of the reformed gas and combustion gas into each reforming tube 6 is uniform, gas reforming will be carried out by the above-mentioned reforming reaction without any problem. However, as the reforming reaction progresses, if the catalyst particles contained in the catalyst layer 8 in a particular reforming tube 6 are crushed or cracked due to rapid thermal changes caused by the reaction, the reforming The internal pressure loss of the catalyst layer 8 in the pipe 6 changes, making it difficult for the reformed gas to flow into the pipe, and the amount of reformed gas flowing into the pipe decreases. As a result, since the p1 reforming tube 6 is cooled by the reformed gas inside, the wall temperature of the reforming tube 6 increases due to the decrease in the amount of reformed gas. Then, as the operating time of the apparatus passes, a difference in tube wall temperature appears between the reforming tube 6 and other reforming tubes 6. In this case, as described above, in this reformer, the average temperature TA of each reforming tube 6 is compared with its own tube wall temperature, and the amount of reformed gas flowing into each tube is adjusted individually based on this deviation. Therefore, the tube wall temperature of each reforming tube 6 is always kept uniform. Furthermore, the average temperature TA of each of the reforming tubes 6 is compared with the limit temperature Ts as described above, and the inflow amount of combustion gas is adjusted based on this deviation. The temperature control reforming temperature is always maintained at the limit temperature T8.

Therefore, by using the reformer with this configuration, each reforming pipe 6
Since it is possible to always keep the tube wall temperature uniform and at the same level as the limit temperature T8, it is possible to prevent the reforming tubes 6 from being damaged by heat as in the conventional case, and to improve the rate of gas reformation in each reforming tube 6. It is possible to improve the quality efficiency and improve the reforming efficiency of the entire apparatus. In addition, in this reformer, since the sleeve pipe 29 is provided concentrically with the reforming pipe 6 and has the same radial width in any circumferential direction from the reforming pipe wall, each reforming pipe 60
The above effect can be further promoted by reducing the temperature difference in the circumferential direction.

Incidentally, in the above embodiment, the case where there are three reforming tubes 6 was described, but
The present invention is similarly applicable to the case where there are two or more than four wires.

〔Effect of the invention〕

As explained above, according to the present invention, even in a configuration in which a plurality of reforming tubes are provided, the tube wall temperature of each reforming tube is made uniform to achieve long life and high efficiency. A highly reliable reforming device capable of carrying out reforming can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a conventional reforming device, FIG. 2 is a sectional view showing the configuration of the upper end of the reforming tube in FIG. 1, and FIG. 3 is a sectional view showing an embodiment of the present invention. 4 are block diagrams showing an example of a tube wall temperature control circuit applied to the present invention. 1... Reformer, 2... Burner, 3... Combustion chamber,
4... Heating channel, 5... Exhaust gas outlet, 6... Reforming pipe, 7... Reformed gas inlet, 8... Catalyst layer, 9...
Center plug, 10...Return path, 11...Reformed gas outlet, 15...Temperature measurement element, 21...Combustion gas line, 22...Combustion air line, 23...Combustion gas adjustment Valve, 24... Combustion air control valve, 25...
Reformed gas line, 26... Reformer tube lower chamber, 27...
Reformed gas control valve, 28... Reformed gas discharge control valve, 2
9...Sleeve pipe, 30...Average temperature calculator, 31
．． 32... Valve controller. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 9 Figure 3

Claims (1)

[Claims] It has a plurality of reforming tubes each having an annular cross section, one end of which is sealed, and a reforming catalyst layer is provided between an inner pipe line and an outer pipe line, and the combustion gas is combusted in a combustion chamber. The heated fluid obtained by the heating is discharged from one end of the reforming tube through the outside thereof to the outside from the other end, and the reformed gas is introduced from the other end of the reforming tube through the reforming catalyst layer. Furthermore, in the reformer configured to allow the combustion gas to flow from one end through the inner pipe line and from the other end, a combustion gas regulating valve provided on a combustion gas line that supplies the combustion gas;
A reformed gas control valve provided on each of a plurality of reformed gas lines for causing the reformed gas to flow into each of the reforming tubes separately, and a tube wall temperature measurement valve of each of the reforming tubes are adjusted. a first valve controller that controls the opening degree of the combustion gas control valve; and a first valve controller that separately compares the average temperature and the temperature measured by each of the temperature measurement elements, and controls the inflow of the reformed gas based on the comparison results. A reformer comprising a tube wall temperature control circuit including a second valve controller that separately controls the opening degree of the corresponding reformed gas control valve in order to adjust the amount of reformed gas.