JPH0319465B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a tube heating furnace for heating process fluids in petroleum refining, petrochemical equipment, and coal liquefaction equipment.

Conventionally, this type of tube heating furnace has two types: a radiant heat transfer section in which a large number of radiant heating tubes are arranged in a combustion chamber equipped with a burner, and a convection heat transfer section in which a large number of heating tubes are arranged in a staggered manner. In combination, the heated fluid introduced into the heating tube of the convection heat transfer section is preheated in the convection heat transfer section, and then introduced into the heating tube of the radiation heat transfer section where it is heated to a predetermined temperature by combustion gas and taken out to the outside. It is common that the

However, in such a configuration, sufficient consideration is given to the piping of the radiant heating tube so that the flame from the burner does not hit the radiant heating tube, but since the radiant heat transfer section is formed inside the combustion chamber, the radiation There was a drawback that the heat transfer part was prone to localized overheating. or,
Fuels were limited to gas fuel and light and heavy oil fuel, and coal, residual oil, etc. could not be used.

In order to eliminate the drawbacks of such conventional methods,
Recently, a radiant section has been connected to the upper part of the fluidized bed combustor, a convection section has been connected to the downstream side of the radiant section, and the connection section between the fluidized bed combustor and the radiant section has been connected to the heating tube in the radiant section. The combustion gas generated in the fluidized bed combustor is narrowed narrower than the spacing, and the combustion gas generated in the fluidized bed combustor flows into the radiant section through the constricted section, and the heating fluid guided to the heating tube arranged along the side wall of the radiant section is heated by radiation heat transfer. A configuration has been proposed in which this is done.

In this configuration, heating in the radiant section is performed mainly by radiation from one side of the heating tube.
Since the combustion gas flow velocity near the heating tube is low, it is most suitable for the above-mentioned furnace, but a furnace that heats by radiation from both sides of the heating tube (the heating tube is placed in the combustion gas flow path away from the side wall) is suitable for this type of furnace. The above-mentioned structure could not be adopted in the combustor, as the high-velocity combustion gas contained in the duct from the fluidized bed combustor caused significant wear and tear, and required expensive pipe material.

The present invention has been made to enable heating from both sides of the heating tube so that fluidized bed combustion can be used in a double-sided heating type furnace, thereby improving thermal efficiency and allowing the furnace to be housed in a low-profile building. be.

Embodiments of the present invention will be described below with reference to the drawings.

The tube heating furnace of the present invention basically includes a fluidized bed combustor 1 and radiant sections 2 and 3, which are connected by a horizontal duct 4, and the hot air generated in the fluidized bed combustor 1 is transferred to the horizontal duct. 4, the combustion gas from the fluidized bed combustor 1 is fed into the radiant sections 2 and 3, and the heating tubes in the radiant sections 2 and 3 are heated by the combustion gas from the fluidized bed combustor 1.

Specifically, the fluidized bed combustor 1 installed on one side of the heating furnace is installed horizontally at an intermediate position in the vertical direction of a narrow and deep combustor main body 5 having a combustion air inlet at one end of the lower part. A fluidized bed 8 is provided by depositing a fluidized medium 7 such as silica sand on the dispersion plate 6 arranged so that the combustion air passes through the dispersion plate 6 and is guided to the fluidized bed 8. A large number of coal feed ports 9 for supplying coal as fuel are provided in the depth direction on the high side wall as shown in FIG. 2, and coal is fed into each coal feed port 9 from a coal hopper (not shown). coal feeder (not shown)
are provided respectively, and a starting burner 10 is further provided toward the depth direction of the fluidized bed 8 to ignite the coal supplied onto the fluidized bed 8.

The radiant sections 2 and 3 are provided beside the fluidized bed combustor 1 and below the horizontal duct 4. Each radiation part 2,
3, heating tubes 11a, 12a, 11b, 12b divided into the same number as shown in FIGS. 2 and 3,
11c, 12c, 11d, 12e, 11f, 12
f, 11g, 12g, 11h, and 12h are arranged in a spiral manner vertically away from the side walls of the radiant sections 2 and 3, and each lower end of each of the heating pipes 12a to 12h of the radiant section 3 is a process fluid supply pipe. The fluid outlet side of each of the heating tubes 12a to 12h is connected to the lower end of each heating tube 11a to 11h of the radiant section 2, which is the fluid inlet side of the heating tube 11a to 11h. and each heating pipe 1
Each fluid outlet side of 1a to 11h is connected to a fluid discharge pipe, and the radiant parts 2 and 3 are connected to the partition wall 13.
The radiant section 2 and the fluidized bed combustor 1 on the upstream side thereof are separated by a partition wall 14, and the combustion gas from inside the fluidized bed combustor 1 enters the radiant section 2 and the radiant section 3,
Each of the heating tubes 11a to 11h and 12a to 12h is uniformly contacted and heated.

Below each of the radiant parts 2 and 3, that is, on the downstream side, there are convection parts 15 and 16 for waste heat recovery, which have a large number of heating tubes (not shown) arranged in a staggered manner. On the downstream side, there are dampers 22, 23 and gas outlets 17, 18 for adjusting the amount of combustion gas introduced into each of the radiant sections 2, 3.

In addition to the fluidized bed combustor 1, 19 is a fluidized bed combustor installed in the heating furnace, and the combustion gas from the fluidized bed combustor 19 also enters the radiant sections 2 and 3 through the horizontal duct 4. 20 is a duct provided so that the pressurized combustion air flowing into the fluidized bed combustor 1 flows upward; 21 is a duct provided in the duct 20 for controlling the amount of combustion air to the fluidized bed combustor 1; This is a damper for adjustment.

With the above configuration, when pressurized combustion air flows in from the supply inlet, it passes through the duct 20 on the inlet side, is guided from the distribution plate 6 to the fluidized bed 8, and begins to flow the fluidized medium 7. Next, start burner 1
When coal is ignited, the portion of the fluidized bed 8 near the burner 10 is heated and reaches a predetermined temperature, and then when coal is supplied from the coal feed port 9, combustion begins. Next, when the adjacent damper 21 is opened to fluidize the fluidized medium and coal is supplied from the corresponding coal feed port 9, it is heated by the adjacent heat. Thereafter, in the same way, the damper 21 on the central side in the depth direction of the fluidized bed 8 is sequentially opened, and coal is supplied and burned. After flowing above the fluidized bed combustor 1, this combustion gas enters the radiant section 2 and the radiant section 3 through the horizontal duct 4.

The combustion gas that entered the upper part of the radiant parts 2 and 3 is
Since the gas outlets 17 and 18 are located below, the gas flows downward, and by adjusting the amount of opening and closing of the dampers 22 and 23, the gas is distributed so that the radiant section 3 side is the low temperature side and the radiant section 2 side is the high temperature side. It will be done.

In the radiant section 2, several heating tubes 11a to 11b are arranged spirally in the vertical direction, and in the radiant section 3, there are heating tubes 12 connected to the heating tubes 11a to 11h.
Since the heating tubes 12a to 12h of the radiant section 3 are arranged, the heating tubes 11a to 11a of the radiant section 2 pass through the heating tubes 12a to 12h of the radiant section 3.
The process fluid as the fluid to be heated led to the heating pipe 1 is heated by the combustion gas in the radiant section 3.
After being uniformly heated from the entire circumference of the heating tubes 2a to 12h, the heating tubes 11a to 11h are further heated by the combustion gas in the radiant section 2.
It is uniformly heated from the entire circumference of 11h and taken out to the outside. On the other hand, the gas that radiated heat in the radiant parts 2 and 3 is
After preheating the process fluid introduced into the heating tubes 12a to 12h by further dissipating heat to the heating tubes (not shown) in the convection sections 15, 16, the process fluid is discharged from the gas outlets 17, 18 and guided to a dust collector (not shown). The dust will be collected and released into the atmosphere.

In the present invention, the heating tubes 11 of the radiant parts 2 and 3
A to 11h, 12a to 12h are heated by directing the combustion gas guided downward from the fluidized bed combustor 1 through the horizontal duct 4, thereby making the temperature distribution and flow velocity uniform, while heating the heating pipes 11a to 11h, 12a
Since the heating is performed uniformly from the entire circumference for ~12 hours, overheating in the radiant parts 2 and 3 can be prevented and the process fluid can be heated efficiently.

Furthermore, in the present invention, the combustion gas generated in the fluidized bed can be introduced separately into the radiant sections 2 and 3, and the amount of introduction can be adjusted, so that the process fluid can be rapidly heated in the radiant section 3 to around the reaction temperature range. After that, it can be heated gently by the radiant section 2, and only the necessary reactions can be stably promoted without causing side reactions or coking.

Note that since the fluidized medium 7 in the fluidized bed 8 gradually decreases along with the combustion gas, it is necessary to periodically replenish the fluidized medium 7 with a supply device, and to blow combustion air into the fluidized bed. Although the case where fluidized air is fluidized and heated to a predetermined temperature with the burner 10 is shown, it is also possible to fluidize it by blowing in high-temperature air, and the number of heating tubes in the radiant sections 2 and 3 is other than that shown in the figure. Of course, various changes may be made without departing from the gist of the present invention.

As described above, according to the tube heating furnace of the present invention, the fluidized bed heating section and the radiant section are provided separately and connected by horizontal ducts, and the combustion gas generated in the fluidized bed is directed below each radiant section through the horizontal duct. By guiding the fluid, the temperature distribution and flow velocity are made uniform, and the heating tube is heated evenly from the entire circumference, so fluidized bed combustion can be used even in furnaces that heat on both sides, and the process fluid can be heated efficiently. can do. Furthermore, the combustion gas generated in the fluidized bed can be distributed and introduced into each radiant section, and the amount introduced can be adjusted, so that after the process fluid is rapidly heated to around the reaction temperature range in a predetermined radiant section, it is then introduced into another radiant section. It is possible to heat gently in the combustion zone, stably promoting only the necessary reactions without causing side reactions or coking, and compared to the type in which a radiant section is installed above the fluidized bed combustion zone. It has excellent effects such as being able to reduce the overall height and being able to be housed in a low building.

[Brief explanation of the drawing]

Fig. 1 is a cutaway front view of the tube heating furnace of the present invention, Fig. 2 is a cutaway side view taken from the direction A-A in Fig. 1, and Fig. 3 is a plan view taken from the B-B direction in Fig. 1. It is. 1 is a fluidized bed combustor, 2 and 3 are radiant parts, 4 is a horizontal duct, 6 is a distribution plate, 7 is a fluidized medium, 8 is a fluidized bed, 10 is a starting burner, 11a to 11h, 12
a to 12h are heating tubes, 15 and 16 are convection parts, 1
7 and 18 are gas outlets, and 22 and 23 are dampers.

Claims (1)

[Claims] 1. In a tube heating furnace that heats process fluids in oil refining equipment, petrochemical equipment, coal liquefaction equipment, etc., the side of a fluidized bed combustor that has a fluidized bed and burns the fuel supplied to the fluidized bed. A plurality of radiating parts are arranged in parallel, each having a gas outlet at the lower part and having an adjustable amount of combustion gas introduced. The heating tubes are connected to each other in order to cross each radiant section, and the upper part of the fluidized bed combustor and the upper part of the radiant part adjacent to the fluidized bed combustor are connected via a horizontal duct. A tube heating furnace characterized by being connected to