Enclosure Structure Device for Process Furnaces

Abstract

The current invention relates to the field of process furnaces design and can be used in oil refining industry, steam boilers and furnaces for heating feedstocks. A body of a process furnace, comprising an internal lining, is also provided with an outer protective coating which is discrete and structurally heterogeneous. The irregularity of the coating structure is provided by a filler. The invention makes it possible to reduce fuel consumption by reducing heat emission and heat loss from a furnace body into the surrounding environment.

Claims

1. An enclosure structure for a body of a process furnace comprising the body with a frame and an internal lining structure, characterized in that the body is covered from an outer surface thereof with a coating which is discrete and heterogeneous by structure and which comprises a mixture of polymers dispersed in water and fillers, the fillers being from 40 to 70% of the volume of the mixture.

2. The body per claim 5, wherein the fillers include expanded perlite.

3. The body per claim 5, wherein the fillers include microspheres.

4. The body per claim 5, wherein thickness of the outer coating is from 0.4 to 2.0 mm.

5. A body of a process furnace comprising an internal lining therein and an outer coating thereon, the coating comprising a mixture of water (from 60 to 30 vol. %) and polymers with fillers (from 40 to 70 vol. %).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] Details, features and advantages of the present invention will be explained in the ensuing description of the embodiments thereof and accompanying drawings, in which:

[0033] FIG. 1 illustrates an example of an enclosure structure of the body of the PF for heating up starting materials;

[0034] FIG. 2 shows an example of an enclosure structure of the body of the PF for primary crude oil processing;

[0035] FIG. 3 depicts an example of an enclosure structure of the body of the PF for heating up starting materials with an additional protective coating; and

[0036] FIG. 4 reflects an example of an enclosure structure of the body of the PF for primary crude oil processing with an additional protective coating;

[0037] Denoted in the drawings are the following positions: 1a body of the furnace; 2an outside frame; 3an integrated structure of the internal lining and thermal; 4an outer coating of the body and frame of the furnace with a discrete composition, heterogeneous by the structure thereof, the composition having thickness of no more than 2.0 mm and comprising, for example, water and a mixture of acrylic polymers and fillers dispersed therein and comprising 40-70% of the volume of the whole composition.

DETAILED DESCRIPTION

[0038] The technical solution relates to the body of process furnaces (PF) and can be used at the metallurgic, chemical and petroleum refining facilities for energy usage reduction and enhancement of the personnel's safety, as well as for additional protection of the PF metallic frame from unfavorable environment factors. Designs of the PF known in the art conduce, to a degree, and mainly due to the use of internal lining, the lowering of heat transfer from the body of PF. However, as it follows from the analysis of the prior art, the problem of decreasing the fuel consumption to compensate for the heat loss from the body has not yet been solved. Increasing the thickness of the furnace lining results in either decreasing the internal space of the furnace leading to the reduction of the output thereof, or in the increase of outer dimensions of the furnace resulting in the increase of the cost of the PF.

[0039] In the proposed invention, a discrete composition, heterogeneous by structure thereof and no more than 2.0 mm in thickness, is applied to an outside surface of the enclosure structure (the PF body).

[0040] Compounds comprising water and a mixture of acrylic polymers and fillers dispersed therein and making from 40 to 70% of the whole composition, or a mixture of latexes and expanded perlites dispersed therein (from 40 to 70% of the whole composition), or a mixture of latexes and microspheres dispersed therein (from 40 to 70% of the whole composition) can be cited as examples of such products.

[0041] Developed at the surface of the body after the polymerization of the compound is a layer of a discrete, heterogeneous coating possessing, as compared with the materials of the PF body and frame, lower heat transfer and heat conductivity.

[0042] The minimal thickness of the coating is limited by the spreading capacity of the composition of the coating. For example, for compositions using microspheres as a filler, the spreading capacity is no less than 0.2 mm, whereas it is no less than 0.4 mm for those using expanded perlite as a filler. Maximal thickness of the coating, namely 2.0 mm, is limited by fire safety regulations for particularly hazardous facilities.

[0043] Where the mixture filler is less than 40% of the whole composition, discrete properties of the coating surface sharply deteriorate. In case it is more than 70%, linear stretching of the finished coating decreases, thus lowering service time of the coating.

[0044] It is only where the quantity of the polymers and fillers is between 40 and 70% that the heat transfer from the surface of the material decreases. Formed is a discrete surface rather than the entire one. The discrete structure of the material has lower heat transfer and conductivity as compared with the entire one. At the same time, the above-identified thickness of the coating prevents the PF body metal from overheating and does not get in the way of controlling the condition of the body visually. Also, a number of fire safety requirements with regard to the PF structure are met herewith as well.

[0045] FIG. 1 exemplifies the PF structure for heating up starting materials.

[0046] The enclosure structure of this PF comprises a layer of internal lining of fire-brick protected from inside by a thermostable filler. There is also an integrated structure of a steel casing of the body and frame. The steel casing of the body and frame is covered with an antirust compound and a protective enamel. Brands and technical characteristics of the materials used for the PF, which depend on the PF operation condition requirements, vendor capacity, and the cost of the materials used, have no impact on the proposed design.

[0047] FIG. 2 shows an example of the PF structure used for primary crude oil processing.

[0048] The enclosure structure of this PF comprises a layer of internal lining of mineral wool mats protected from inside by a thermostable filler and layers of thermal from mineral wool boards. There is also an integrated structure of a steel casing of the body and frame. The steel casing of the body and frame is covered with an antirust compound and a protective enamel. Brands and technical characteristics of the materials used for the PF, which depend on the PF operation condition requirements, vendor capacity, and the cost of the materials used, have no impact on the proposed design.

[0049] In both above examples, the end element is the steel casing. It is known that steel has high value of heat transfer, and protection paint does not decrease the value of heat transfer.

[0050] Heat transfer coefficient is a value characterizing the rate of heat dissipation, and it is defined by the ratio of the current of heat released by a surface to the temperature difference between this surface and adjacent environment. A design heat transfer coefficient, according to the Building code (CNR (Construction Norms and Rules) 2.04.14-88, as applied, appendix 9) is equal to 35 W/m.sup.2 C.

[0051] An open metallic (or brick or concrete) surface possesses high value of the heat transfer coefficient which is due to physical properties of the materials used for the PF body. The object of the proposed design is to change physical structure of the outer heat dissipating surface that would result in decreasing heat transfer therefrom. In doing so, the possibility of visual monitoring of the PF body surface condition should be kept, and the overheating of the body should be avoided.

[0052] Generally, the enclosure structure comprises three basic elementsa body, a frame securing the integrity of the body, and an internal lining (potentially with thermal elements). In some cases, a strengthened design of the lining, such as in open-hearth furnaces, serves as the body and frame as well.

[0053] Unlike the traditional body structure comprising the internal lining (thermal) and body with frame, the proposed PF enclosure structure comprises four elements: a body 1, a frame 2, an aggregate 3 of internal lining and thermal, and an outer protective coating 4, no more than 2.0 mm in thickness, formed by a discrete composition, heterogeneous by structure thereof, such as water and a mixture of acrylic polymers and fillers dispersed in water and containing from 40 to 70% of the total volume of the composition.

[0054] Examples of these compositions are water and a mixture of acrylic polymers and fillers dispersed therein and containing from 40 to 70% of the total volume of the composition; or water and a mixture of latexes and expanded perlite (the mixture containing from 40 to 70% of the total volume of the composition) dispersed therein; or water and a mixture of latexes and microspheres (from 40 to 70% of the total volume of the composition) dispersed therein.

[0055] Due to lower, as compared with that of the material of the PF body, heat transfer and heat conductivity of the additional coating of the enclosure structure of the PF, heat loss from the body and frame of the PF into the atmosphere decreases. Thus, the proposed design results in lowering fuel consumption to compensate for the heat loss from the PF body into surrounding air.

[0056] The maximal thickness of the protective coating, equal to 2 mm, is limited by the necessity to assure visual monitoring of the condition of the PF surface.

[0057] The limiting of the volume of the polymers and filler used in the protective coating to 40-70% of the total volume results from the finding that if their volume is less than 40%, the decrease of the heat transfer from surface is insufficient and does not outweigh the prior expenses, whereas where the volume of the mixture of polymers and filler is more than 70% of the total volume, the capacity of the protective coating to linear stretching decreases, resulting in the destruction of such coating after the furnace shutdown.

[0058] A mixture of butadiene-styrene latex, acrylic polymers, ammonia, and water with a mixture of such fillers as expanded perlite, quartz, zinc oxide and titanium dioxide can serve an example of the composition of the protective coating according to the proposed design.

[0059] Weight percentage of a solvent (water) is 47%, weight percentage of nonvolatile substances is 53%, the latter comprising 23% of polymeric components and 28% of noncombustible inorganic components, the nonvolatile inorganic components comprising 25% of silicon oxide, 28% of titanium oxide, 19% of calcium oxide, 20% of zinc oxide, 5% of potassium oxide, and 3% of ferrous oxide.

[0060] It was established as a result of the research of the characteristics of the protective coating of the above-identified composition that the density of the coating is 410 kg/m.sup.3; specific heat capacity is 1.120 kJ/kg C.; the coefficient of heat transfer is 2.0-3.0 W/m.sup.2 C.; coating combustibilityCC1.

[0061] For comparison, the coefficient of heat transfer from a metallic surface to surrounding air, according to the Building code (CNR 2.04.14-88, as applied, appendix 9) is equal to 35 W/m.sup.2 C.

[0062] Compared below are two variants of calculation of heat loss from the PF bodywithout the protective coating and with the same.

[0063] Variant 1 with no protective coating (FIG. 1).

[0064] Heat transfer resistance

[00001]$R=\frac{1}{1}+\frac{}{}+\frac{1}{2},$

where
1heat absorption coefficient50 W/m.sup.2 C.
thickness of the enclosure structure0.2 m
average heat conductivity coefficient for the whole enclosure structure1.0 W/m.sup.2 C.
2coefficient of heat transfer from the surface35 W/m.sup.2 C.
Rdesign resistance to heat transfer0.25 m.sup.2 C./W.

[0065] Heat loss from the structure under consideration

[00002]$-q=\frac{t-t.Math..Math.3}{R},$

where
tambient temperature inside the furnace800 C.
t3temperature of surrounding air0 C.
qdesign heat loss3144 W/m.sup.2.

[0066] Variant 2 with protective coating (FIG. 3).

Note: to simplify the comparable estimation, the change of thickness of the enclosure structure and of the heat conductivity resulting from applying the protective coating is not taken into account.

[0067] Heat transfer resistance

[00003]$R=\frac{1}{1}+\frac{}{}+\frac{1}{2},$

where
1heat absorption coefficient50 W/m.sup.2 C.
thickness of the enclosure structure0.2 m
average heat conductivity coefficient for the whole enclosure structure1.0 W/m.sup.2 C.
2coefficient of heat transfer from the surface3.0 W/m.sup.2 C.
Rdesign resistance to heat transfer0.55 m.sup.2 C./W.

[0068] Heat loss from the structure under consideration

[00004]$-q=\frac{t-t.Math..Math.3}{R},$

where
tambient temperature inside the furnace800 C.
t3temperature of surrounding air0 C.
qdesign heat loss1446 W/m.sup.2.

[0069] The change of heat transfer of the enclosure structure of the PF makes it possible to have heat loss from the PF body 2.2 times lower.