JPH09137903A - Rectangular multi-tubular one-through boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a controller while facilitating adaptation to a partial load by a method wherein a unit evaporation part is constituted of a gas burner which generates a combustion gas allowing securing of a specified degree of evaporation, a heat exchange part securing a specified amount of steam and two sets of unit evaporation parts are arranged to form a steam generating part. SOLUTION: A unit evaporation part 2 is constituted of a gas burner 5 which generates a combustion gas allowing securing of a half of the maximum degree of evaporation and a heat exchange part 4 (heat transfer tubes) which ensures the maximum degree of evaporation from the combustion gas of the burner 5 and two sets of the unit evaporation part 2 are arranged in parallel to form a steam generating section 1. In this case, to avoid drop in the efficiency, the density of a heat transfer surface at the heat exchange part 4 is set larger gradually in substance from the upstream side to the downstream side of a gas flow. Thus, the rated capacity of the gas burner 5 can correspond to a half load thereby simplifying a controller while allowing adaptation to a partial load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular multi-tube type once-through boiler. More specifically, the present invention relates to a rectangular multi-tube once-through boiler capable of easily responding to a partial load.

[0002]

2. Description of the Related Art Conventionally, a large number of prismatic multi-tube type once-through boilers have been used because legal regulations are loose in the industrial world. The steam generation part of this square multi-tube once-through boiler is
Generally, as shown in FIG. 4, a front portion d of a rectangular thin box body d in which the heat transfer tube groups a, b, and c constituting a heat transfer surface are housed.
₁ , a premixed gas burner e is provided, and a gas outlet f is provided at the rear part d ₂ . In FIG. 4, the heat transfer tube group a is a bare tube, the heat transfer tube group b is a finned tube, and the heat transfer tube c is a spiral finned tube.

In the rectangular multi-tube once-through boiler having such a structure, since a boiler engineer having a legal qualification is not required, its control is also made high / low / off simple. There is.

However, in the conventional rectangular multi-tube type once-through boiler, since a gas burner e commensurate with the rated maximum capacity is provided, as shown in FIG.
The fuel gas system is provided with a flow rate adjusting valve g, which adjusts the flow rate and adjusts the load. Therefore, there is a problem that an expensive and sophisticated control device is required although the control content is simple. In FIG. 5, reference numeral h indicates a flow meter, and reference numeral v indicates a fuel cutoff valve.

Further, the gas burner e, which is commensurate with the rated maximum capacity, is inevitably large in size, so that it is difficult and expensive to manufacture as compared with the one commensurate with half the capacity. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. Even though the control device is simplified, it is possible to easily deal with partial loads. Moreover, it is an object of the present invention to provide a square multi-tube once-through boiler that can use a gas burner that is small and easy to manufacture.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a rectangular multi-tube through-flow boiler, and a combustion means for generating combustion gas capable of ensuring an evaporation amount of 1/2 of the maximum evaporation amount, and a combustion means from the combustion means. A unit evaporation unit is configured by a heat exchange unit that secures an evaporation amount of 1/2 of the maximum evaporation amount by the combustion gas, and two unit evaporation units are arranged in parallel to configure a steam generation unit. The present invention relates to a rectangular multi-tube once-through boiler.

In the prismatic multi-tube type once-through boiler of the present invention, the heat exchanging section adjusts the temperature of the combustion gas from the combustion means within a range of 1500 to 1000 ° C., and a temperature adjusting heat transfer surface. It is preferable to have an adiabatic space provided on the downstream side of the temperature control heat transfer surface, and the heat transfer surface density in the heat exchange section is essentially the density of the gas flow from the upstream side to the downstream side. It is preferable that the smaller ones are the larger ones.

[0009] Here, among those whose density is essentially reduced from the upstream side to the downstream side of the gas flow, the heat transfer surface located upstream of the gas flow is included in the ones having the higher density. A heat transfer surface having a heat transfer surface density smaller than the heat transfer surface density may be provided on the downstream side of the gas flow.

[0010]

Since the rectangular multi-tube type once-through boiler of the present invention is constructed as described above, both combustion means are turned on at the maximum load, and only one combustion means is turned on at the intermediate load. I can deal with it. Therefore, the configuration of the control device is simplified and the cost is reduced.

Further, since the capacity of each combustion means, for example, the capacity of the gas burner may be about half that of the conventional gas burner, the gas burner can be easily manufactured and the cost of the gas burner can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.

FIG. 1 is a sectional view showing a steam generating section of a rectangular multi-tube type once-through boiler according to the present invention. The steam generating section 1 includes two unit evaporation sections 2 capable of ensuring an evaporation amount half the rated maximum evaporation amount.
They are arranged in parallel. Here, the rated maximum evaporation amount is, for example, 2 tons / hour.

Specifically, this prismatic multi-tube type once-through boiler has a thin box body 3 having side walls 31 formed of water-cooling walls constituting the steam generating section 1 and provided at the center thereof. The water cooling wall (partition wall) 32 is divided into two in the gas flow direction, and the heat transfer tube groups 4 and 4 constituting the heat exchange section are arranged in a predetermined arrangement in each of the two divided chambers, and before that. Premixed gas burners 5 and 5 are arranged in a part (left side in the drawing) 33, and a rear part (right side in the drawing)
34 is provided with gas outlets 35, 35. Although the gas outlet 35 is also partitioned in FIG. 1, the gas outlet 35 does not necessarily have to be partitioned (see FIG. 2).

Here, the heat transfer tube group 4 constituting the heat transfer surface is
For example, in order to suppress the generation of NO _X, to 1500 to combustion gas temperature disposed on the front surface of the burner 5 100
A heat transfer tube group 41 for adjusting gas temperature, which is adjusted to a range of 0 ° C.,
Main heat transfer tube groups 42, 4 arranged at a predetermined distance downstream of the gas temperature adjusting heat transfer tube group 41 to form a heat insulating space 36 that oxidizes CO into CO _2.
3, 44, and their respective heat transfer tubes are arranged substantially at right angles to the gas flow.

The temperature control heat transfer tube group 41 is, for example,
The gas burner 5 is composed of a first row arranged in front of the gas burner 5 and a second row arranged in a staggered arrangement behind the first row with a predetermined distance. The pipe pitch between the first row pipes, the pipe pitch between the second row pipes, and the pipe pitches between the first row and the second row are appropriately adjusted according to the pipe size used.

Further, since the combustion gas is cooled and the volume of the main heat transfer tube group 42, 43, 44 is reduced while passing through this tube group, the volume of the main heat transfer tube group 42, 43, 44 is reduced, and thus the flow velocity of the gas passing through the tube group is reduced. However, in order to avoid a decrease in heat transfer efficiency, the heat transfer surface density is set to be small on the upstream side and large on the downstream side. For example, the first pipe group 42 on the upstream side has a staggered arrangement of bare pipes, and the second pipe group 43 and the third pipe group 44 on the downstream side have a staggered arrangement of spiral finned pipes. Here, as a matter of course, the heat transfer surface density of the third tube group 44 is made higher than the heat transfer surface density of the second tube group 43.

For the sake of convenience of the structure of the heat transfer surface, as shown in FIG. 2, a tube group 45 having a heat transfer surface density locally smaller than the heat transfer surface density on the upstream side is provided on the downstream side, and steam is generated. The generation unit 1A may be formed. The point is that the heat transfer surface density on the downstream side is essentially higher than the heat transfer surface density on the upstream side.

Next, with reference to FIGS. 1 and 3, the operation of the rectangular multi-tube type once-through boiler configured as described above will be described. Here, the rated maximum load is an evaporation amount of 2 tons / hour.

(1) At rated maximum load The fuel cutoff valves V ₁ and V ₂ are opened, and the burners 5 and 5 are burned at the rated maximum load. The combustion gas from each of the burners 5 and 5 has a gas temperature of 1500 to 1000 due to the temperature control heat transfer tube groups 41 and 41.
Adjusted to the range of ° C. This suppresses the generation of NO _X. Combustion of the combustion gas whose temperature is adjusted by the temperature-adjusting heat transfer tube groups 41, 41 is promoted by the adiabatic spaces 36, 36, and CO is oxidized into CO ₂ . In this way, the gas completely combusted in the heat insulating space 36 is then cooled by the main heat transfer tube groups 42, 43, 44 to a predetermined temperature, for example, 3
It is cooled to 50 ° C. and discharged from the gas outlet 35.

The steam generated by the temperature control heat transfer tube group 41 and the main heat transfer tube group 42, 43, 44 is collected in a header (not shown) and then bracked by a brackish water separator (not shown). It is supplied by piping to the place of use, for example, a heating device or a reaction kettle.

(2) At 1/2 load The fuel cutoff valve V ₁ (or V ₂ ) is opened and the burner 5 is burned at the rated maximum load. The gas combusted in the burner 5 is heat-exchanged with the heat transfer tube group 4 while being cooled by the heat transfer tube group 4 arranged corresponding to it and discharged from the gas outlet, similarly to the above. Produces steam.

As described above, according to this embodiment, it is possible to cope with a 1/2 load by simply opening or closing one of the fuel cutoff valves V, and the control system is remarkably simplified. Accordingly, the structure of the control device is simplified and the cost thereof is reduced.

[0024]

As described in detail above, according to the present invention,
Since the rated capacity of the combustion means such as a burner can correspond to 1/2 load, a small one can be used as the combustion means such as a burner and the production thereof can be performed at low cost. That is an excellent effect.

Further, since the 1/2 load can be dealt with by simply turning on or off the combustion means such as one burner, the structure of the control system can be remarkably simplified, and the structure of the control device can be remarkably simplified accordingly. In addition, an excellent effect that the cost can be reduced can also be obtained.

Further, the gas temperature from the combustion means is set to 150.
In a preferred embodiment of the present invention, which includes a heat transfer surface for adjusting temperature adjustment for adjusting the temperature in the range of 0 to 1000 ° C. and a heat insulating space provided immediately after the heat transfer surface, NO _X emission and CO emission are suppressed. Excellent effect can also be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a steam generating part of a rectangular multi-tube through-flow boiler of the present invention.

FIG. 2 is a cross-sectional view of another example of the heat transfer surface configuration of the steam generating unit.

FIG. 3 is a simplified control block diagram of a fuel system of the equiangular multitubular once-through boiler.

FIG. 4 is a cross-sectional view of a steam generating portion of a conventional rectangular multi-tube type once-through boiler.

FIG. 5 is a simplified control block diagram of a fuel system of a conventional rectangular multi-tube type once-through boiler.

[Explanation of symbols]

 1 Steam Generation Part 2 Unit Evaporation Part 3 Thin Box Body 31 Side Wall 32 Water Cooling Wall (Partition Wall) 33 Front 34 Rear 35 Gas Outlet 36 Heat Insulation Space 4 Heat Transfer Tube Group 41 Heat Transfer Tube Group 42 Temperature Control Tube Group (No. 1) 1 tube group) 43 Main heat transfer tube group (2nd tube group) 44 Main heat transfer tube group (3rd tube group) 5 Premixed gas burner V Fuel cutoff valve

Claims (4)

[Claims] 1. A prismatic multi-tube once-through boiler, which comprises combustion means for generating combustion gas capable of ensuring an evaporation amount of 1/2 of the maximum evaporation amount, and combustion gas from the combustion means causes a maximum evaporation amount of 1 Unit heat vaporization section for ensuring a vaporization amount of / 2, and a steam generating section is constituted by arranging two unit vaporization sections in parallel to form a rectangular multi-tube flow-through. boiler. 2. The heat exchange section is provided on a temperature adjusting heat transfer surface for adjusting the temperature of the combustion gas from the combustion means in the range of 1500 to 1000 ° C., and on the downstream side of the temperature adjusting heat transfer surface. The rectangular multi-tube through-flow boiler according to claim 1, further comprising a heat insulating space. 3. The heat transfer surface density in the heat exchange section is essentially set such that the density becomes small from the upstream side to the downstream side of the gas flow and becomes large. The rectangular multi-tube through-flow boiler according to 1. 4. A heat transfer surface having a heat transfer surface density lower than a heat transfer surface density of a heat transfer surface located upstream of the gas flow is provided downstream of the gas flow. The rectangular multi-tube once-through boiler according to item 3.