The tube-type furnaces are main customers of combustible on ORF,
therefore their optimal operation is defining for economics of an oil refining complex.
The progressive engineering decisions, foreseen in the projects of furnaces during exploitation
are step-by-step lost and coefficient of performance is slashed on tens percents. However,
if the coefficient of wear of main design clusters of furnaces is not yet great, there is
a possibility of recovery of a primal level COP. The optimization of operation of tube-type
furnaces requires (demands) first of all conducting comprehensive them investigation with usage
of modern instruments for mining and realization of a complex of measures on recovery of work
capacity of tube-type furnaces, rise them COP. The look-alike operations were held in 1997-98
years at the Baku oil refining associations AZERNEFTIANADJAG
and AZERNEFTJAG
. The method
of application of conducting of investigation of tube-type furnaces accompanying them technological
accounts, subsequent analysis of results and development of concrete measures on optimization of
operation of tube-type furnaces held on above named factories, can form the basis for conducting
similar investigations on furnaces of technological complexes of the refineries which have lost
the primal plant-performance figures.
Oil refining industry-one of the most power-intensive branches. The tube-type furnaces on Oil Refining Factory (ORF) are main customers of energy as gaseous and liquid fuel, therefore keeping up of a high level of profitability of their operation, that is coefficient of performance (COP), is defining for economics of all oil-refining complex. Envisioning during designing tube-type furnaces most progressive at present engineering decisions, the designers provide maximum accessible COP. However on-stream furnaces with current of time there is an intellectual aging of designer solutions, physical wear of constructions; in result the operation furnace is degraded, is sharply slashed her (it) COP. The practice of exploitation of tube-type furnaces is frequently directional, first of all, on obtaining of finite technological result, i.e. heating of the determined bulk of raw up to placed (installed) temperature. Amount of combustible expended at it, quite often remain behind frameworks of concerns of producing peoples, as frequently combustible incinerated in furnace, are the own products of waste-handling.
Therefore problem of rise of performance working technological furnaces is rather actual. The maiden and major stage in this direction, as demonstrates expertise, is the conducting comprehensive Investigation of tube-type furnaces and mining of a complex of measures, which one should be produced (worked out) ground such Investigation.
In 1997-1998 years were held all-up Investigations of tube-type furnaces of a vertical-torch type two plants ELOU-AVT-6. These plants were constructed at the end of 70 and kickoff 80 years on the Baku factories and have received the greatest propagation in territory former USSR. The furnaces manufactured in Germany by the corporation Grimma.
The Investigations were spent within the framework of the program TACIS, generated (set up) by the European Union for CIS. The operations on Investigation of furnaces were spent together with the specialists of the company Stork Engineers and Contractors B.V. (Holland-Germany).
The results the Investigations, held in November, 1998 on ELOU-AVT-6 of a factory "AZERNEFTJAG" are most interesting. By results of the Investigation was exhausted the Report, the brief withdrawals from which one are resulted below. The deductions and the sentences of the Report can interest scientifically-a technical public and serve as a manual for optimization of operation furnaces and their reconstruction.
The assessment of works of furnaces after removal of regime indexes and gathering
of the items of information on substitutions and state of furnaces is completed by calculus
them COP. In accounts, except for indexes of boards removed from nominal instruments C and A of
plant, and tooling data, the data's obtained from express portable gagging instruments,
given by the company Stork Comprimo were utilized: a computer gas analyzer of a brand
IMK 3000P and instrument of a brand
Raynger Bi LTDL 2
, measuring temperature
of heated surfaces with the help of an invisible heat (Infra-red rays). By the evaluator IMK 3000P
,
were instituted: a contents in flue gases СO2, O2, CO,H2S,
SO2, NO, NO2, coefficient of surplus of air-"λ",
magnitude of draught, and also flue-gas temperature on outputs (exits) of furnaces and temperature of fresh air.
The results of gagings of skin-temperature of furnaces testify as to exceeding mean design temperature of a surface (t=60 °C), and about significant local overheating reaching on capping up to 200-220 °C, that speaks about a wear or dip of internal calorific insulation. As a result of a heat loss from bodies of furnaces in some times have exceeded design indexs.
Though the nozzles were in a satisfactory state, however their working resource on outcome the
working indexes are much lower design. The state of dampers adjusting feeding of secondary air,
eliminates possibility of regulation of its of feeding. In result suck up a great many of excess air,
that rises(elevates,improves,raises) and slashes COP the furnace. The flue gases from furnaces drive
through boiler-utilizators having poor efficiency, and working on self-draught because of mortality
of induced-draft fans. By the characteristic negative factor (captured evaluator IMK 3000 P
)
were very much heats of an output (exit) of flue gases from furnaces- on the average 650 °C, at
moderate exceeding on coefficient of surplus of air-"λ" =1,53 … 1,63.
The held accounts of calorific performance have shown, that COP of furnaces 51-53 % is in limits, i.e. he has decreased from a design level on 20 %. The communal dip of an overall performance raw coil-pipes, component from a design level 84-87 % takes place. Comparing these indexes with indexes of exceeding of temperature of an output(exit) of flue gases it is possible to draw a conclusion about significant dip warm assimilating of capacity raw coil-pipes. The decrease twice of mean thermal stress of a surface of tubes coil-pipe testifies to this. The dip warm assimilating of capacity of grocery worm pipes results in necessity to give in furnace an excessive amount of combustible.
At Investigation of raw coil-pipes the erosive wear in six last on a course of raw, tubes of irradiation in a place of turn of move of environment was captured, that, apparently, is connected to substantial growth of speed of raw on a lease of intensive vaporization. It results in a quick(rapid) wear of removals from the inside, abatement of their thickness and necessity of their often substitution. For getting rid of the given lack it is possible to replace last on a course of raw of a tube of a worm pipe from a diameter 150 with 200 mm, as a result of which travelling speed of raw will be diminished in 2,1 times and the phenomena of erosion is stopped(terminated,discontinued).
Some structural elements of furnaces morally have become outdated and have exhausted(settled), appreciably, working resource. To such it is possible to refer lining(liner) from temperature-resistant concrete and nozzles.
Now new created furnaces are equipped by lining (liner) from the facilitated removable
temperature-resistant materials. They have low gravity and large thermal resistance. If instead
of temperature-resistant vermikulitceramsitbeton liner of furnaces facilitated lining from mineralwadding
of tables and insulating felt of felt, the thermal resistance of lining(liner) will increase in 2,6 times.
However lining(liner) should be be to be calculated and pick up so that temperature on an internal surface
of the metallically plating has not gone down to temperatures of condensation point
and exceeded
her(it) on 10-15 °C. The substitution of lining (liner) of boards on one more effective can give
saving of combustible about 2000 ton in year.
Now in use on furnaces the nozzles such as SODZ morally and physically have become outdated. The presence in flue gass of monoxide of carbon speaks about incompleteness of combustion of combustible at presence of significant surplus of air. It testifies to bad blending of combustible with air. There are also factors speaking about low ecological indexes, among which one strong noise by operation and presence in flue gases of nitric oxides. Now is tested and some new types nozzles, permitting are inserted to work with low "λ", less noisy and ecologically clean.
The flue gases which are coming out of of boiler-utilizators, save a significant thermal energy. The rise communal COP of the block furnaces could be promoted also by installation after boiler-utilizators, on a course of flue gases, padding heat exchange devices, in which one it would be possible to work out heated water for sanitary-home needs of a factory.
The state of main design clusters of tube-type furnaces can be estimated as good (hull, ladder, platforms) and satisfactory (raw coil-pipe, plating, lining (liner), nozzles); and the decrease of a state of some clusters furnaces up to satisfactory is explained as absence of a due maintenance (cleanings, maintenance work) and predatory calorific duty. The investigation of a state of furnaces results us in the deduction, that in a construction of furnaces their designers and manufacturers stipulated a sufficient spare of hardness and longevity. Outgoing from this we come to the deduction, those furnaces should be saved, under condition of optimization of their operation and fractional reconstruction.
It is ground held investigations, of accounts and analysis of the obtained results the concluding concerning possibility of optimization of operation furnaces and sentence on their reconstruction was made.
The optimization of operation of furnaces should consist from: of clearing of surfaces coil-pipes from depositions for meliorating them warm assimilating of capacity, coercion in operative conditions of dampers of secondary air on nozzles and closure of openings in the body of furnaces, through which one is sucked excessive air, iterating of a constant stack-gas analysis on a contents CO and O2, conducting of a complex of operations on recovery of temperature-resistant concrete of lining (liner) and calorific insulation in places of its(her) wear, recovery of complete scale exploitation of a disposal system of heat of flue gases. The realization of tendered measures will allow to optimize operation of the block of furnaces and to push up their communal COP up to a design level.
Parsing data's of investigation it is possible to suspect, that for furnaces all plants,
were in exploitation about 20 years, there will be similar problems, i.e. the extent and nature of
a deterioration of separate clusters and will be desire for a manual plants and factories to lead
(carry outspend) retrofit of furnaces and to retrieve their design COP, and can be and exceed it(him).
In this operation, undoubtedly, the data's obtained as a result of held investigation can help but,
certainly, in each concrete case it would be desirable to lead(carry outspend) investigation under
the method of application utilized at investigation of furnace of plant ELOU-AVT-6 of a factory AZERNEFTJAG
The sentences on reconstruction of the inspected tube-type furnaces, together with measures on optimization of their operation, can promote rise COP of furnaces and their block as a whole, provide their effective exploitation, caretaking of energy and meliorating of ecological indexes ORF.