Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D25/00—Devices or methods for removing incrustations, e.g. slag, metal deposits, dust; Devices or methods for preventing the adherence of slag
  • F27D25/008—Devices or methods for removing incrustations, e.g. slag, metal deposits, dust; Devices or methods for preventing the adherence of slag using fluids or gases, e.g. blowers, suction units
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L10/00—Use of additives to fuels or fires for particular purposes
  • C10L10/06—Use of additives to fuels or fires for particular purposes for facilitating soot removal
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J3/00—Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
  • F28G1/00—Non-rotary, e.g. reciprocated, appliances
  • F28G1/16—Non-rotary, e.g. reciprocated, appliances using jets of fluid for removing debris

Definitions

• the present invention relates to a method for cleaning hot surfaces of ovens, as well as an installation and granules for its implementation.
• ovens In many fields of industry, and in particular of the petrochemical industry, ovens, boilers, air coolers are used, hereinafter called “ovens” and provided with heat exchangers having surfaces in particular metallic and in particular bundles mostly tubular. These heat exchangers often have fouling, in particular on the heating fluid side, in the form of deposits, the composition of which varies according to the fluids (liquid or gaseous) which supply the calories to the exchanger.
• the present invention overcomes these drawbacks, in fact it relates to a method of cleaning by disintegration of deposits on the surfaces of furnaces in operation, implemented dry.
• an oxidizing agent in particulate form is sprayed onto the surfaces to be cleaned; the dry oxidizing agent itself is sprayed into a dry gas flow under pressure.
• dry is meant substantially free of water.
• ovens in particular all ovens and boilers comprising surfaces hot interiors, notably metallic, in particular refinery ovens, atmospheric distillation, vacuum distillation, reformer ovens, of the cylindrical oven or cabin oven type, or even double oven comprising two radiation zones and one or more convection zones common, as well as crackers and heat exchanger boilers.
• surface is meant more generally any hot surface of the furnace fouled by a deposit coming from a fuel, and in particular metal surfaces.
• the cleaning is carried out on the fly, that is to say without the installations being stopped.
• Surfaces, particularly metallic ones, are then commonly brought to temperatures of 200 to 1000 ° C., the temperatures being different in the radiation zones and in the convection zones.
• This cleaning according to the invention makes it possible to carry out the disintegration and elimination of deposits in a single step and results from the combination of two effects.
• these deposits contain combustible materials corresponding to the unburnt fuels generally used for reheating, these deposits can be eliminated by "chemical” or “thermal” effect due to the combustion of the deposits present on the hot surface which s 'ignite on contact with the oxidizing agent particles, this combustion causing disintegration of the deposits and burning the combustible materials present in these deposits.
• the oxidizing agent being in the form of a particle, the projection of these particles also has a "mechanical” effect linked to the speed of the particles when they come into contact with the surfaces to be cleaned. The combination of these two effects ensures the disintegration and elimination of deposits.
• oxides, peroxides and persalts of chromium, manganese, chlorine, sulfur, nitrogen or boron such as chromates, dichromates, permanganates, chlorates, nitrates, nitrites or borates of alkali metals. , alkaline earth, or ammonium, or mixtures thereof.
• the oxidizing agent according to the invention is in the form of granules.
• the particle size is between 0.5 and 2.5 mm and in particular between 1 and 2 mm. More particularly, a particle size of approximately 1.5 mm for ammonium nitrate granules has been shown to be particularly effective.
• the mechanical effect due to the projection of the granules according to the invention can be amplified by simultaneously projecting a hard particulate material.
• Sand can be used for this purpose, for example.
• the grain size of the sand is then chosen between 0.5 and 2 mm.
• cleaning sand When using a mixture of oxidizing agent and particulate material, depending on the degree of fouling of the surfaces to be treated, cleaning sand can be used in a proportion of up to 20% by weight.
• the density in the form of loose granules is for example between approximately 0.5 ⁇ 103 kg.m ⁇ 3 and 1.5.103kg.m ⁇ 3.
• the dry gas flow entraining the particles in contact with the surfaces to be cleaned must have, according to the invention, a speed sufficient to entrain the particles and allow them to complete the chemical and thermal effect of local combustion by the mechanical effect of attack on the deposits. .
• This mechanical effect is achieved in particular when the speed of the particles of oxidizing agent, and possibly of the hard particulate material, is between 100 and 250 m.s ⁇ 1. A speed of 130 to 200 m.s ⁇ 1 proved to be particularly effective.
• the present invention also relates to an installation for cleaning by disintegration of deposits on the hot surfaces of ovens by spraying an oxidizing agent in particulate form on these surfaces in a dry gas flow under pressure.
• the installations according to the invention include a piping for transporting the dry gas flow connected at one end to a source of dry gas under pressure, and at the other end to a means for spraying the gas-particle mixture of the type nozzle.
• This installation also comprises a particle tank provided with a means for dosing the particles.
• This metering means opens into the transfer piping and for this purpose, between its two ends, the transfer piping is provided with a connection with the metering means of the reservoir.
• the piping is at least in flexible part.
• the particle tank is pressurized, and provided with a gravity metering means, the pressure in the transfer piping and the pressure prevailing in the tank being compatible with the use of a valve. mechanical allowing the mechanical regulation of the dosing by gravity. These pressures can for example be substantially balanced.
• pressures of the order of 5.105 to 10.105 Pa for the compressed gas are preferred;
• the internal diameter of the piping is of the order of 25 to 50 mm;
• the means for projecting the gas-particle mixture of the nozzle type, and preferably of the Venturi type may have an internal diameter of the outlet opening of the order of 9.5 to 11 mm, and a length of 150 to 200 mm.
• the piping comprises at least one flexible part.
• this installation is intended to be actuated by a man who directs the nozzle and the jet emitted by the nozzle towards the deposits in the furnace.
• the means of projection can be fixed on a lance, which the man directs towards the surfaces to be cleaned, from all openings and / or manholes of the oven in operation. These can be the manholes on the periphery of the oven, the access door, the manholes, and even the explosion hatches.
• hoses As flexible hoses, it is preferable to use hoses with double woven reinforcement.
• these flexible pipes are chosen from a material which conducts electric current, which makes it possible to avoid the phenomena of static current, and therefore the risks of sparks and of explosion. This particular mode is very useful in refineries. The installation itself is then connected to ground.
• the present invention also relates to granules comprising at least one oxidizing agent for their application to the implementation of the method according to the invention, the particle size of which is between 0.5 and 2.5 mm, preferably 1 to 2 mm.
• the oxidizing agent can be chosen from the oxides, peroxides and persalts of chromium, manganese, chlorine, sulfur, nitrogen or boron such as chromates, dichromates, permanganates, chlorates, nitrates, nitrites or borates of alkali, alkaline earth, or ammonium or mixtures thereof.
• the oxidizing agent constituting the granules is ammonium nitrate.
• the method according to the invention was implemented in a cylindrical furnace of a hydrocracking unit of a oil refinery. It is an oven operating with a constant load.
• the oxidizing agent used is ammonium nitrate with a uniform particle size of approximately 1.5 mm, the density of the compound in the form of loose granules being 1.103kg.m ⁇ 3.
• This "pressure sandblaster” type device is connected to the compressor. It receives the granulate and routes it to the outlet in a dry gas flow at the speed necessary for spraying at the nozzle outlet.
• This device operates under pressure, according to the principle of gravity with regard to the passage of particles or granules from the tank to the piping used for transfer.
• the pressure prevailing in the particle tank is approximately equal to the pressure of the compressed air coming from the compressor through the transfer piping, which is the pressure prevailing below the granules or particles.
• the granulate is entrained by the gaseous flow of compressed air and enters the transfer piping via a metering means which allows the quantity of granule to be adjusted precisely. introduced. This regulation is carried out using a metering valve with mechanical regulation.
• the pipes are flexible with a double woven frame; they conduct electrical current.
• the internal diameter of the pipe is 32 mm.
• the nozzle used is of the Venturi type and nozzles were used having an outlet opening of 9.5 mm and lengths of 150 mm.
• the exit speed of the granules was then between 130 and 200 ms ⁇ 1.
• compressors which can develop a power of between approximately 50 and 150 CV, and which can provide a pressure of between 4.105 and 10.105 Pa, these values being given for information only.
• the choice of the projection nozzle must also take into account the type of intervention.
• Example 1 The procedure of Example 1 was reproduced with the same type of installation for treating an oven where more stubborn deposits fouled the pipes. A mixture comprising the same granule and 15% by weight of dried washed sand, and calibrated between 0.5 and 1 mm was used.
• the method and installation according to the invention are particularly useful for finding or maintaining in oven installations an efficiency during use and even after a long use equivalent to the start-up efficiency. , that is to say, without waiting for the annual shutdowns of industrial sites for fouling.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Cleaning In General (AREA)
• Detergent Compositions (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Manufacturing Of Micro-Capsules (AREA)
• Fertilizers (AREA)
• Pretreatment Of Seeds And Plants (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9384279

Family Applications (1)

Country Status (5)

Cited By (6)

Citations (4)

• 1989
  • 1989-07-28 FR FR8910244A patent/FR2650384B1/fr not_active Expired - Fee Related
• 1990
  • 1990-07-24 EP EP90402118A patent/EP0410867B1/de not_active Expired - Lifetime
  • 1990-07-24 AT AT90402118T patent/ATE108199T1/de not_active IP Right Cessation
  • 1990-07-24 DE DE69010418T patent/DE69010418T2/de not_active Expired - Fee Related
  • 1990-07-24 ES ES90402118T patent/ES2056408T3/es not_active Expired - Lifetime

Patent Citations (4)

Also Published As

Similar Documents

Legal Events