JPS5828503B2 - Combustion heater with double casing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventional naturally vented burners for direct-fired combustion heaters have an air conditioning device through which combustion air is introduced into the combustion chamber of the heater.

Noise generated within the combustion chamber is dissipated through the air conditioner to the vicinity of the heater, and additional noise is generated by the passage of combustion air through the air conditioner.

This additional noise also dissipates around the heater.

Additionally, in conventional naturally vented burners, the fuel ejector is unshielded and radiates additional noise that radiates around the heater.

Current environmental requirements require the addition of noise damping devices' to natural vent burners to limit the escape of noise to the surroundings of the heater.

While conventional noise attenuation devices effectively prevent noise from escaping, they serve no other useful purpose, and they add to the cost of the furnace without improving heat dissipation efficiency.

Fuels used in refineries and petrochemical plants often contain enough sulfur to cause corrosion problems.

One effective way to avoid sulfur corrosion in heaters is to
The purpose is to operate the heater by raising the surface temperature of the heater to a temperature higher than the condensation temperature range of H2SO3 and H2SO4.

However, such operation results in significant heat loss from the heater to its surroundings and cannot be maintained under all environmental conditions.

The problems of the prior art with respect to noise escape and sulfur corrosion are solved by the present invention in a particularly novel, useful, unobtrusive and simple manner.

A direct-fired combustion heater includes an inner casing having at least one naturally vented burner extending through the inner casing and an outer casing spaced apart from the inner casing to form a passageway for communicating ambient air to the burner. Equipped with.

It is desirable that the passageway be provided with a sound-absorbing inner surface to attenuate noise.

It is a feature of the invention that in particular low frequency noise generated in the combustion chamber is substantially prevented from escaping from the combustion chamber and the burner.

In the present invention, the increase in surface temperature of the inner casing can be adjusted by controlling the thickness and density of the inner thermal insulation lining.

In the present invention, the double casing arrangement eliminates various environmental changes that affect the surface temperature of the internal casing.

Therefore, the temperature of the inner casing can be kept above the temperature range at which sulfur condenses during operation over all ambient temperatures except when the ambient temperature is extremely low.

Higher surface temperatures can generally be obtained by using a denser refractory material, which also has greater fracture resistance, greater strength and less porosity.

Dense refractory materials are impermeable to gases and do not allow corrosive gases to pass through to the casing surface, and can accumulate enough gas to condense acids that corrode the casing surface during heater outage. Not at all.

In accordance with the present invention, there is no need to effectively insulate the surface of the inner casing, thereby eliminating the need for low density refractory materials or dual material refractory constructions, thus reducing costs.

This method generally reduces the refractory requirements.

Another feature of the invention is the provision of a passageway with a sound-absorbing surface between the inner and outer casings.

The inner surface of the outer casing can be lined with a material that has heat insulating and sound absorbing effects, so it can surround heat and sound very effectively. You may.

The outer casing is generally arranged around the inner casing so that noise generated from the combustion chamber through the surface of the inner casing is absorbed into the lining of the outer casing.

Furthermore, heat losses from the surface of the inner casing are compensated by preheating the combustion air introduced through the passage between the inner casing and the outer casing.

Since the surface of the inner casing is shielded from all ambient conditions except air temperature (ie, wind speed, precipitation, etc.), the surface temperature of the inner casing can be more effectively controlled.

There is no need to provide the burner with a noise damping device.

The thermal efficiency of the heater is improved.

Another feature of the present invention is that heaters of the type contemplated herein can be manufactured using inexpensive materials.

The heater is easy to design, manufacture and maintain and is compatible with its intended function.

The invention will now be described by describing the preferred embodiments in detail with reference to the accompanying drawings.

As best seen in FIGS. 2 and 5, the heater consists of a vertical inner casing 11 (cylindrical in FIG.
(box-shaped in the figure).

The casing 11 has a bottom 12 and a top 13 which surround a combustion chamber 14 .

The heater is supported on a pedestal 15 by a structural member 16 and a suitable pedestal and associated ladders and steps (
(not shown).

The burner 17 enters the combustion chamber 14 from the bottom 12.

A convection box 18 is provided above the top 13, and the convection box 18
A chimney 19 is formed above so that the combustion gases rise from the combustion chamber 14 through the convection box 18 and then into the chimney 19.

The fluid in one or more paths generally flows back through the heater to provide non-contact heat exchange with the hot combustion gases.

The path of fluid typically passes through a convection tube bundle 22 and then through a radiant tube 23 in the combustion chamber 14.

A key feature of the invention is the provision of an outer casing 24 spaced from the bottom 12 and the inner casing 11 to form a passageway 26 providing communication between the atmosphere 27 and the burner 17.

Preferably, the outer casing 24 extends near the top 18 of the combustion chamber 14 and has an opening 28 for introducing ambient air.

As best seen in FIGS. 2 and 5, burner 11
has a gun that is connected to a suitable fuel tube 29 and injects fuel through the ceramic block 33.

The combustion air conditioning device controls the supply of combustion air to the burner 1T in a manner known from the prior art.

The inner casing 11 having an outer surface 25 is lined with a hydraulic fireproof insulation material 36 on its inner surface.

In order to protect the casing 11''f from corrosion due to sulfur, it is desirable to maintain the temperature of the casing 11 above the condensation temperature range of sulfur oxides.

The density and thickness of the hydraulic fireproof insulation material 36 and/or the firebricks 39 are appropriately designed to meet this purpose.

The design of such refractory insulation is well known in the art.

Noise escape from combustion chamber 14 and burner 17 is controlled by surrounding the air entering burner 17 through passage 26 and opening 28 .

This method generally eliminates the need for sound damping devices.

The inner surface 31 of the outer casing 24 is preferably provided with an acoustic and/or thermal insulation lining 38 .

The lining 38 is a glass fiber having a density of about 3 pounds per cubic foot (about o, ol/c11t) or 1
Approximately 6 pounds per cubic foot (approximately o, i g7crit)
) is effective.

This is because they are low density long fiber materials with insulating properties and can act as a resistor to the high air velocities experienced within the passageways 26.

[Brief explanation of the drawing]

FIG. 1 is an elevational view of a vertical cylindrical heater according to the present invention. FIG. 2 is an enlarged elevational view of the heater shown in FIG. 1, with a portion thereof cut away and enlarged. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an elevational view of a box-shaped heater according to the present invention. FIG. 5 is an enlarged elevational view of the heater of FIG. 4, with a portion thereof cut away and in section. 6 is a sectional view taken along line 6-6 in FIG. 5. FIG. 11...Inner casing, 14...Combustion chamber, 17...Burner, 18...Convection box, 24...Outer casing, 26・・・・・・
・Passage, 29... Combustion pipe, 33... Ceramic block, 36... Fireproof insulation material, 39
・・・・・・Refractory brick.

Claims (1)

[Claims] 1 an inner casing surrounding a combustion chamber and having a first end; at least one burner communicating with the combustion chamber and penetrating the casing through the first end; A direct-fired combustion heater comprising: an outer casing spaced from said first end to define a flow communication passageway; and an insulating and sound absorbing surface disposed in said passageway. .