CA1211345A - Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. the flue gas side of a furnace or boiler - Google Patents
Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. the flue gas side of a furnace or boilerInfo
- Publication number
- CA1211345A CA1211345A CA000402177A CA402177A CA1211345A CA 1211345 A CA1211345 A CA 1211345A CA 000402177 A CA000402177 A CA 000402177A CA 402177 A CA402177 A CA 402177A CA 1211345 A CA1211345 A CA 1211345A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- composition
- water
- furnace
- flue gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B43/00—Preventing or removing incrustations
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Combustion & Propulsion (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Incineration Of Waste (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
APPLICANTS: JOE INGE OLGART JOHANNESSON, BENGT GORAN LUNDSTROM
SVEN-GUNNAR SVENSSON, CLIMATIC AB, DALF INTERNATIONAL AB
TITLE: Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. the flue gas side of a furnace or boiler ABSTRACT OF THE DISCLOSURE
Process and device for loosening and removing soot and solid coatings on surfaces in enclosed spaces such as the flue gas side of a furnace or boiler. In the case of a furnace, covers and flue gas ducts to the flue gas side are sealed to form a closed chamber, which is supplied with unpressurized steam.
Characterizing the process is that the steam, before being introduced into the enclosed space, is saturated with a cleaning composition, which includes synthetic tensides, alkali, complexing agents, a corrosion inhibitor and environ-mentally safe solvents and solvent vehicles.
The cleaning of the metal surface is done in one or more steps and is followed by a passivating step for the metal surface, whereby the surface is coated with a passivating agent which counteracts continued deposits on the metal surface.
The device is characterized in that it comprises a vessel for liquid cleaning composition, said vessel being connected via a line to a reduction valve, through which water flows to a steam generating chamber, which includes means for vapourizing the water in conjunction with said composition. The combined steam of water and composition is conducted via a steam line to the enclosed space to be cleaned, e.g. the flue gas side of a furnace.
SVEN-GUNNAR SVENSSON, CLIMATIC AB, DALF INTERNATIONAL AB
TITLE: Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. the flue gas side of a furnace or boiler ABSTRACT OF THE DISCLOSURE
Process and device for loosening and removing soot and solid coatings on surfaces in enclosed spaces such as the flue gas side of a furnace or boiler. In the case of a furnace, covers and flue gas ducts to the flue gas side are sealed to form a closed chamber, which is supplied with unpressurized steam.
Characterizing the process is that the steam, before being introduced into the enclosed space, is saturated with a cleaning composition, which includes synthetic tensides, alkali, complexing agents, a corrosion inhibitor and environ-mentally safe solvents and solvent vehicles.
The cleaning of the metal surface is done in one or more steps and is followed by a passivating step for the metal surface, whereby the surface is coated with a passivating agent which counteracts continued deposits on the metal surface.
The device is characterized in that it comprises a vessel for liquid cleaning composition, said vessel being connected via a line to a reduction valve, through which water flows to a steam generating chamber, which includes means for vapourizing the water in conjunction with said composition. The combined steam of water and composition is conducted via a steam line to the enclosed space to be cleaned, e.g. the flue gas side of a furnace.
Description
~Z~3~5 Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.c~. the flue gas side of a furnace or boiler The present invention relates to a process for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. soot and solid coatings formed during the operation of a furnace ~r boiler on the surfaces of space of the furnace forming the ~lue gas side, covers and flue gas ducts to the flue yas side being sealed to form a closed chamber and steam, saturated with a special cleaning composition accord-ing to the invention, is supplied to the flue gas side. The process according to the invention can be carried out in one or more steps, depending on the composition and thickness of the coatings.
The invention also comprises a device for carrying out the process. The invention will be described in more detail below and illuminated with examples for the case where the enclosed space, ~he surfaces of which are ~o be freed of coatings and thus cleaned, is the flue gas side of a furnace or boiler, but i~ will be obvious that the process and the device can just as easily be applied to the cleaning of other enclosed spaces, e.g. the interior walls of tanks and large vessels.
The background of the invention Continually rising oil prices make it necessary to try all possible means to reduce the cost of oil heating of houses, apartment ~ouses and factories by seeing to it that the efficiency of the furnaces is as hi~h as possible. Optimum ener~y use of furnaces means lower fuel cons~nption, lower maintenance costs and a cleaner environrnent. At the same time as attempts are made to reduce the direct fuel costs and increase efficiency of the furnaces, attempts are made to avoid corrosion on the furnace walls as well. The main ~.
~Z1~3~i cause of corrosion is the sulphur in -the fuel, primarily fuel oil. During combus-tion this sulphur forms with the oxygen in the combustion air sulphur dioxide, which sub-sequently gives rise to sulphuric acid, which is very corrosive to the furnace walls. Modern furnaces have a relatively high efficiency. In a clean oil-burning furnace about 90 ~ of the heat content of the oil is utilized. When the oil-is burnedr however, soot is also produced in addition to heat, and some of this soot is deposited on the furnace walls, partly in the form of loose soot and partly as a solid coating. Soot is an extremely good insulation material, five times better as asbestos. When the thickness of the soot layer on the walls of the flue gas space are 2 mm for e~ample, there is a heat transfer loss in the furnace wall of nearly 20 % and when the coating thickness is between 3 and 4 ~m, the heat transfer has reached about 50 %. The problem can also be expressed as follows: an increase in the flue gas temperature of 50C
from 200C to 250C for example with a carbon dioxide content of 10 %, reduces the efficiency of the furnace by about 3 %. This points out the great economic importance of preventing an unnecessary rise in the -flue gas temperature, e~g. as a result of reduced heat absorption ~ecause of solid coatings on the furnace surfaces.
Factors contributing to reduced heating costs in burning fossil fuels include cleaning and soot removal in furnaces and removal of solid coatings which appreciably reduce the heat transfer capacity and thus the efficiency of the 3~ furnace, resulting in turn in higher energy consumption.
The solid coatings on the furnace walls and the convection portions, consist pri~arily of sulphates, which are very difficult to remove by conventional mechanical cleaning methods or b~ traditional sweeping, In certain types of ~5 cast f~lrnaces, the coatings can result in a reduction of surface area in the flue ~as ducts in the convection portion -making flue gas evacuation ~ore difficult 3~i There is no complete knowledge of the contents of combustion residues in furnaces. Analyses of coatings from oil-burning units reveal, in addition to combustion residues such as oil coke and flame soot, also hiyh contents of ash particles, silicon, asbestos, sodium, calcium, sulphur dioxide ancl a number of heavy metals such as vanadium, nickel, iron, copper, cadmiumf lead, zinc, mercury and chromium. Buxning certain t~pes of fuel o~ls produces relatively high contents of vanadium, sulphur and iron sulphate in the furnace coatings. The coatin~s can thus vary widely in chemical composition. This places great demands on the cleaning agent The cleaning agent must not be harmful to the furnace nor to the environment, effectively removing soot and coatings on furnace walls but at the same time not producing corro-sion or brittleness of the furnace material.
Several methods are known and generally used for removingsolid coatings in e.g. furnaces n The methods used up co now are primarily ~ased on the use of a neutralizing agent, i.a.
ammonia, primarily for controlling the pH value of the cleaning steam to a level which is sufficient to neutralize the sulphuric acid normally formed when steam comes into contact with solid coatings. The neutralizing agents used are inexpensive and easily available and when carefully used produce rather ~ood cleaning~ Despite this utility, these neutrali2ing agents have certain disadvantages however which make their use more difficult and make the cleaning process less effective.
According to one method, described in Swedish Lay-open Print 7415358~6 (publication number 387 430)~ steam is used to remove bo~h soot and solid coatings. The method has proved to be effective and relatively inexpensive.
The method in~olves however subjecting the furnace to a certain amount of wear at each cleaning. Wear arises because of corrosion~ since the steam condenses on the furnace walls ~Z~3~S
and reacts with the sulphur compounds in the coatings to form sulphuric acid. This is highl~ corrosive also in the drainage system throuyh which the dissolved sludge must be removed during cleaning. To~neutralize the sllldgel before it runs out into the drain, caustic soda is usually used, which is pl~ced on the bottom surface of the furnaee. It is however difficult to achieve a perfect dosage of so~a to preven~ environmental damage, due to too high or too low pH value. Also certain risks are involved for workers handling the soda. Furthermore it is not possible to eliminate corrosion on the ~urnace walls with the aia of the caustic soda. Aftex the steam treatment, the dissolved coatings are removed by rinsing with water. It is possible to add a basie agent to the rinse water whieh can neutralize the sulphuric acid, but the amount of sulphurie acid is usually so large that too much time must be devoted to rinsing with a basic a~ent. After water rinsin~, the cleaned furnace surfaces are treated with an approved basic agent to neutralize any remaining sulphur in pores, welding joints and the like~ This method, which is designated System Vapor, is complicated and expensi~e in addition to having the above described problems According to a ~rocess described in Norwegian Patent Speci-fication ~2654, in cleaning heating surfaces on the flue gas slde of furnaces, preheaters and the like, one starts with a mixture consisting of water, preferabl~ in steam form, and ammonia. Carbon dioxide is added to this mixture in the form of a gas mixture or a solution of carbonated ammonium salts and during the period in which this mixture is allowed to act on the heat s~lraces to be cleaned, a continuous cooling of the heat surfaces is ef~ected from the water side by means of water, salt solution, cold air or otherwise The inventive idea behind the process accord-ing to the patent specification, is that the added carbondioxide together with the am~onia will achieve an increase in the inner pressure in the capillaries of the deposits~
~ z~.~3~5 which will lead -to a bursting of the coating. To achieve this effect, i.e. achieve an additional pressure increase, the patent specification discloses that the process can be amplified b~ temporary heatingi This pressure increase achieved thereby is said to be the cause of the powerful burstiny effect. The patent speci~ication also discloses that according to one embodiment of the process, the desired effect is`~chieved in a more advantageous manner by alter-natingly cooliny and heating the waterside, the heating being done by stea~ for example, hot water or the like, and the cooling being effected in ~arious ways which require more work, time and expense. According to one embodiment, it is disclosed that cooling is effected by means o softened water and salt solution is recommended for cooling other parts of the flue gas space. The patent specification also points out that when neutralizing free sulphuric acid occurring in the deposits, the reaction heat generated has a disadvantageous effect or a completely inhibiting effect on the process, especially on the condensation of water ar~onia vapours which is unavoidable for the process. In the patented process, the continuous cooling from the water-side ;s prevented by the heat generation.
~erman ~uslegeschrift 27 0~ 716 describes a process which is di~ided into several steps. In the first step, ammonia-water is introduced into the flue gas space in the furnace by means of steam for a period of 1~2 hours. The ammonia used is not mixed into the steam before it is introduced into the flue gas space. Rather~ ammonia vapours are intro-duced into the upper portion of the flue gas duct to becleaned ~hrough openings designed there~or, and the ammonia is finally di~ided by means of a spray device for water, also in the upper portion of the flue gas space. In the meantime, steam is introduced into the lower portion of the flue gas duct through steam jets, whereby the steam produces an additional fine division of the ammonia vapou~.
The Ausle~eschrift discloses that it is advantageous to ~Z~L34~i arrange the spray device or water as high as possible in the flue gas space and the injectors as low as possiblP in the space, so that the water can effect a cleaning process from top to bottom while the steam flows from bottom to top.
During this step of the total process, there is no satura-tion o~ steam with neutralizin~ ayent, i.e. c~mmonia. Rather, it is disclosed that the ammoniawater used suitably has a 25 % contè~t of ammoni~, the rest being water.
After the initial treatment with ammoniawater plus steam, there is the next step which involYes introduction, simultaneously wit~ the ammonia ~apour, of water in such limited amounts that the pH Yalue of the collected dropping water does not fall below 7.4. It is stated that during this step it ~s ~ery i~portant that the con-tinued supply of ammonia vapour be dosed in response to the measured pHvalue.
Then there is the third step in the process, according to which a small amount of ammonia plus a very large amount of water is supplied to the flue gas side. It is specified that initially a very small amount of water is sprayed in, the proportion of water b~ing continually raised as the cleaning of the vessel continues.
After the amount ratio ammonia/water has been continually changed during t~e preceding step to maintain a pH value in the dropping water of abo~e 7.4, a final water spraying is done. By way of conclusion~ the process according to the German Ausle~eschrift is characterized by initially spraying in ammoniawater which is finally divided by means o separate steam injected in another part o~ the unit, where-after a mixture of ammonia and water is introduced, where the ratio of amount between these two components is continually regulated to hold the pH above 7.4.
Pinall~, Danish Lay-open Print 122 369 describes an agent for cleaning the ~lue gas side o~ furnaces. The agent 3~
consists in principle of two components, namely a) ordinary anionic, amphoteric or non-ionic tensides and b) chemical compounds which ~o a far reaching degree are subjected to thermal decomposition with heavy generation of yases, preferably ammonia and carbon dioxide. According to the Lay-open print, the following demands are placed on the means used: 1. it must haYe a high wetting and penetrating effect, 2,'it must have a good neutralizing effect, 3. ik must produce a heavy generation of gas at elevated tempera-ture and finallyr the medi~ must have minimal tendency toform coatings, The inventi~e idea can be said to lie in point 3, i.e. that the means ~ust produce a heaYy gas generation at elevated te~peratureD Examples of components having this characteristic o~ producing heavy gas genera tion, preferably ammonia and carbondioxide, are ammonium carbonatel ammonium ~icarbonate, ammonium carbamate or carba~ide. According to the lay~open print, it is also possible to use gas generatiIlg compounds which do not split the ammon;a, i.e. compounds which have been used as blowing agent in the manufacture of foamed plastic articles. It is stated that w~ are dealing with compounds which at elevat~d temperature split off nitrogen, e.g. aæodicarbonamide with several compounds. According to the lay-open print, it is also possible to use oxygen generating compounds, e.g.
carbamide peroxide adducts and finally it is also possible to use a com~ination of substances, which are thermally decomposed with gas generation.
The description discloses how the cleaning agent in question can be used: a solution in water or possibly partially a dispersion of the means being sprayed as such into the flue gas space o~ the furnacer using for this purpose a spray device commonly available on the market with su~ficient capacity, e.g. those available for spraying of gardens against harmful insects.
All of the known processes and means described above for 34~i cleaning the flue gas side of furnaces have various dis-advantages which can be avoided with the present invention.
The present invention relates to a process, according to which steam, prior to being supplied to the flue gas side for example of the ~urnace, is saturated with a com-position which, if the process is carried out in only one step, or a~ternatively in the first step of a multistep process, i.a. produces an increase in the pH value of the ]o steam to a level which is sufficient and necessary for creating a basic environment, in which the components of the composition during the cleaning process transform all harmful sulphur compounds in the coatings and environmental-ly harmful heavy metals into harmless salts which can be easily remo~ed from the bottom of the furnace. Saturating the steam with the composition in question practically completely elim;~natesthe formation of sulphuric acid with accompanying problems according to the traditional processes.
~ sulphuric acid is still formed upon contact o~ the steam with the sulphur compounds in the coatings, this acid is immediately neutralized by alkali in the composition, such as alkali hydroxide, silicates or phosphates. Normally, however, as was mentioned, other compounds are formed in the reaction between the components of the composition and the sulphur compounds, which will be discussed in more detail below.
The composition used in the process according to the inven-tion consists of a mixture, which primarily and in principle comprises synth~tic tensides, or~anic complexing agents, alkali which in addition to the aboYe mentioned effects (i.e. achieving a basic environment and neutralizing any sulphuric acid formed) also have a direct grease dissolving and cleaning effect, environmentally safe solvents and solvent vehicles, corrosion inhibitor, passivating additive, sur~actants and water. The make up of the composition is directed in each individual cleaning case to the type of s pollutants occurring and the coatings in the spaces to be cleaned and to the thickness of the coating. In practice, several steps must often be combined to achieve a satis-factory clean result. Thus it is not possible -to recommend a uniform composition for all types of furnace units and coatings.
When usiny a cleaning process in two steps for a ~urnace unit for example, the first step is suitably carried out in a basic en~ironment as mentioned above, while the second step, for remoYing for example hard to remove burned on residue on furnace walls, such as oil coke and flame soot as well as iron sulphate coatings~ is performed in an acid environment.
Thus the scope of the in~ention encompasses the use of a number of special cleaning a~ents which best fulfil the requirements. The in~ention fulfils even present hiyh environmental standards. This is especially true with regard to acid components in coatings such as sulphur compounds and harmful heavy metals such as vanadium, nickel, iron, copperr cadmium~ lead, zinc~ mercury and other metal ionsO These are neutralized and converted into harmless compounds or salts in the cleaning process in one or more steps, i.e~ before the waste products enter the drainage system. Our tests have shown that waste products from the cleaning process contain only half or one fourth of the amount of environmentally hazardous substances permissible by the environmental authorities.
The co~positions used in the process accordin~ to the invention are in the form of premixed additives, either YiScous liquids or powders, which are mixed with water be~ore u5e.
For cleanin~ and removing soot ~rom ~urnaces and removin~
coatin~s in lar~e furnace units~ a composition in liquid 3~;
form appears to be advantageous A powder composition has the advantage that it need not be protected from frost, which can be important in certain cases.
-S The process according to the invention in combination withthe special cleaning cvmpositions can be used in closed tanks for example and all types of combustion systems with fossil ~-uels ~or achie~i~ a particularly effective cleaning, soot removal and removal of coatings by means of a non-damaging treatment, which i,a. eliminates the danger ofcorrosion damage to the metal surfaces. The process is considera~ly more simple an~ less time-consuming than methods used up to now and the treatment result is decidedly better, thus providing economic advantages over traditional methods. The process according to the invention also provides an effective corrosion protection of furnace walls for example. The compositions used according to the inven-tion are environmentally safe and do not damage hands or clothings. Nor are they poisonous, thus making handling ~hereof completely safe. For bulk handling however, it is recommended that protective glasses and rubber gloves be used to prevent splashing in the eyes or lengthy skin contact. In the process according to the invention, waste products from the treatment of furnaces or tanks are collected on the bottom of the furnace or tank in the form of a slud~e. No special disposal prescriptions are required for the bottom sludge, There is no poisonous discharge and thus no separate drain cleaning or detoxification is re-quired. At the same time as the metal surface is cleaned down to the metal in the process according to the invention, materials which are normally dan~erous in normal cleaning of furnaces, are converted to harmless salts and enYiron-mentally safe xesidue. After the cleaning treatment, an anticorrosi~e surface passivatin~ layer is formed on the furnace wall, which also has the e~fect that soot will not fasten as easily to the furnace wall.
ll ~2~13~
Said anticorrosion effect and the formation of a passivating layer on the furnace wall is suitably achieved by performing the passivation in a separate step, after the primary clean-ing process~ By formation of a surface-passivating layer, the life of the furnace can be appreciably extended. The passivating layer formed on the ~urnace wall consis-ts of iron or zinc phosphate and iron oxide and has a weight of 200-lOOO~m~/m . Examples of passi~ating agents will be gi~en below.
In summary, the process according to the invention has the following characteristics for furnace cleaning:
1. The furnace is turned of~.
The invention also comprises a device for carrying out the process. The invention will be described in more detail below and illuminated with examples for the case where the enclosed space, ~he surfaces of which are ~o be freed of coatings and thus cleaned, is the flue gas side of a furnace or boiler, but i~ will be obvious that the process and the device can just as easily be applied to the cleaning of other enclosed spaces, e.g. the interior walls of tanks and large vessels.
The background of the invention Continually rising oil prices make it necessary to try all possible means to reduce the cost of oil heating of houses, apartment ~ouses and factories by seeing to it that the efficiency of the furnaces is as hi~h as possible. Optimum ener~y use of furnaces means lower fuel cons~nption, lower maintenance costs and a cleaner environrnent. At the same time as attempts are made to reduce the direct fuel costs and increase efficiency of the furnaces, attempts are made to avoid corrosion on the furnace walls as well. The main ~.
~Z1~3~i cause of corrosion is the sulphur in -the fuel, primarily fuel oil. During combus-tion this sulphur forms with the oxygen in the combustion air sulphur dioxide, which sub-sequently gives rise to sulphuric acid, which is very corrosive to the furnace walls. Modern furnaces have a relatively high efficiency. In a clean oil-burning furnace about 90 ~ of the heat content of the oil is utilized. When the oil-is burnedr however, soot is also produced in addition to heat, and some of this soot is deposited on the furnace walls, partly in the form of loose soot and partly as a solid coating. Soot is an extremely good insulation material, five times better as asbestos. When the thickness of the soot layer on the walls of the flue gas space are 2 mm for e~ample, there is a heat transfer loss in the furnace wall of nearly 20 % and when the coating thickness is between 3 and 4 ~m, the heat transfer has reached about 50 %. The problem can also be expressed as follows: an increase in the flue gas temperature of 50C
from 200C to 250C for example with a carbon dioxide content of 10 %, reduces the efficiency of the furnace by about 3 %. This points out the great economic importance of preventing an unnecessary rise in the -flue gas temperature, e~g. as a result of reduced heat absorption ~ecause of solid coatings on the furnace surfaces.
Factors contributing to reduced heating costs in burning fossil fuels include cleaning and soot removal in furnaces and removal of solid coatings which appreciably reduce the heat transfer capacity and thus the efficiency of the 3~ furnace, resulting in turn in higher energy consumption.
The solid coatings on the furnace walls and the convection portions, consist pri~arily of sulphates, which are very difficult to remove by conventional mechanical cleaning methods or b~ traditional sweeping, In certain types of ~5 cast f~lrnaces, the coatings can result in a reduction of surface area in the flue ~as ducts in the convection portion -making flue gas evacuation ~ore difficult 3~i There is no complete knowledge of the contents of combustion residues in furnaces. Analyses of coatings from oil-burning units reveal, in addition to combustion residues such as oil coke and flame soot, also hiyh contents of ash particles, silicon, asbestos, sodium, calcium, sulphur dioxide ancl a number of heavy metals such as vanadium, nickel, iron, copper, cadmiumf lead, zinc, mercury and chromium. Buxning certain t~pes of fuel o~ls produces relatively high contents of vanadium, sulphur and iron sulphate in the furnace coatings. The coatin~s can thus vary widely in chemical composition. This places great demands on the cleaning agent The cleaning agent must not be harmful to the furnace nor to the environment, effectively removing soot and coatings on furnace walls but at the same time not producing corro-sion or brittleness of the furnace material.
Several methods are known and generally used for removingsolid coatings in e.g. furnaces n The methods used up co now are primarily ~ased on the use of a neutralizing agent, i.a.
ammonia, primarily for controlling the pH value of the cleaning steam to a level which is sufficient to neutralize the sulphuric acid normally formed when steam comes into contact with solid coatings. The neutralizing agents used are inexpensive and easily available and when carefully used produce rather ~ood cleaning~ Despite this utility, these neutrali2ing agents have certain disadvantages however which make their use more difficult and make the cleaning process less effective.
According to one method, described in Swedish Lay-open Print 7415358~6 (publication number 387 430)~ steam is used to remove bo~h soot and solid coatings. The method has proved to be effective and relatively inexpensive.
The method in~olves however subjecting the furnace to a certain amount of wear at each cleaning. Wear arises because of corrosion~ since the steam condenses on the furnace walls ~Z~3~S
and reacts with the sulphur compounds in the coatings to form sulphuric acid. This is highl~ corrosive also in the drainage system throuyh which the dissolved sludge must be removed during cleaning. To~neutralize the sllldgel before it runs out into the drain, caustic soda is usually used, which is pl~ced on the bottom surface of the furnaee. It is however difficult to achieve a perfect dosage of so~a to preven~ environmental damage, due to too high or too low pH value. Also certain risks are involved for workers handling the soda. Furthermore it is not possible to eliminate corrosion on the ~urnace walls with the aia of the caustic soda. Aftex the steam treatment, the dissolved coatings are removed by rinsing with water. It is possible to add a basie agent to the rinse water whieh can neutralize the sulphuric acid, but the amount of sulphurie acid is usually so large that too much time must be devoted to rinsing with a basic a~ent. After water rinsin~, the cleaned furnace surfaces are treated with an approved basic agent to neutralize any remaining sulphur in pores, welding joints and the like~ This method, which is designated System Vapor, is complicated and expensi~e in addition to having the above described problems According to a ~rocess described in Norwegian Patent Speci-fication ~2654, in cleaning heating surfaces on the flue gas slde of furnaces, preheaters and the like, one starts with a mixture consisting of water, preferabl~ in steam form, and ammonia. Carbon dioxide is added to this mixture in the form of a gas mixture or a solution of carbonated ammonium salts and during the period in which this mixture is allowed to act on the heat s~lraces to be cleaned, a continuous cooling of the heat surfaces is ef~ected from the water side by means of water, salt solution, cold air or otherwise The inventive idea behind the process accord-ing to the patent specification, is that the added carbondioxide together with the am~onia will achieve an increase in the inner pressure in the capillaries of the deposits~
~ z~.~3~5 which will lead -to a bursting of the coating. To achieve this effect, i.e. achieve an additional pressure increase, the patent specification discloses that the process can be amplified b~ temporary heatingi This pressure increase achieved thereby is said to be the cause of the powerful burstiny effect. The patent speci~ication also discloses that according to one embodiment of the process, the desired effect is`~chieved in a more advantageous manner by alter-natingly cooliny and heating the waterside, the heating being done by stea~ for example, hot water or the like, and the cooling being effected in ~arious ways which require more work, time and expense. According to one embodiment, it is disclosed that cooling is effected by means o softened water and salt solution is recommended for cooling other parts of the flue gas space. The patent specification also points out that when neutralizing free sulphuric acid occurring in the deposits, the reaction heat generated has a disadvantageous effect or a completely inhibiting effect on the process, especially on the condensation of water ar~onia vapours which is unavoidable for the process. In the patented process, the continuous cooling from the water-side ;s prevented by the heat generation.
~erman ~uslegeschrift 27 0~ 716 describes a process which is di~ided into several steps. In the first step, ammonia-water is introduced into the flue gas space in the furnace by means of steam for a period of 1~2 hours. The ammonia used is not mixed into the steam before it is introduced into the flue gas space. Rather~ ammonia vapours are intro-duced into the upper portion of the flue gas duct to becleaned ~hrough openings designed there~or, and the ammonia is finally di~ided by means of a spray device for water, also in the upper portion of the flue gas space. In the meantime, steam is introduced into the lower portion of the flue gas duct through steam jets, whereby the steam produces an additional fine division of the ammonia vapou~.
The Ausle~eschrift discloses that it is advantageous to ~Z~L34~i arrange the spray device or water as high as possible in the flue gas space and the injectors as low as possiblP in the space, so that the water can effect a cleaning process from top to bottom while the steam flows from bottom to top.
During this step of the total process, there is no satura-tion o~ steam with neutralizin~ ayent, i.e. c~mmonia. Rather, it is disclosed that the ammoniawater used suitably has a 25 % contè~t of ammoni~, the rest being water.
After the initial treatment with ammoniawater plus steam, there is the next step which involYes introduction, simultaneously wit~ the ammonia ~apour, of water in such limited amounts that the pH Yalue of the collected dropping water does not fall below 7.4. It is stated that during this step it ~s ~ery i~portant that the con-tinued supply of ammonia vapour be dosed in response to the measured pHvalue.
Then there is the third step in the process, according to which a small amount of ammonia plus a very large amount of water is supplied to the flue gas side. It is specified that initially a very small amount of water is sprayed in, the proportion of water b~ing continually raised as the cleaning of the vessel continues.
After the amount ratio ammonia/water has been continually changed during t~e preceding step to maintain a pH value in the dropping water of abo~e 7.4, a final water spraying is done. By way of conclusion~ the process according to the German Ausle~eschrift is characterized by initially spraying in ammoniawater which is finally divided by means o separate steam injected in another part o~ the unit, where-after a mixture of ammonia and water is introduced, where the ratio of amount between these two components is continually regulated to hold the pH above 7.4.
Pinall~, Danish Lay-open Print 122 369 describes an agent for cleaning the ~lue gas side o~ furnaces. The agent 3~
consists in principle of two components, namely a) ordinary anionic, amphoteric or non-ionic tensides and b) chemical compounds which ~o a far reaching degree are subjected to thermal decomposition with heavy generation of yases, preferably ammonia and carbon dioxide. According to the Lay-open print, the following demands are placed on the means used: 1. it must haYe a high wetting and penetrating effect, 2,'it must have a good neutralizing effect, 3. ik must produce a heavy generation of gas at elevated tempera-ture and finallyr the medi~ must have minimal tendency toform coatings, The inventi~e idea can be said to lie in point 3, i.e. that the means ~ust produce a heaYy gas generation at elevated te~peratureD Examples of components having this characteristic o~ producing heavy gas genera tion, preferably ammonia and carbondioxide, are ammonium carbonatel ammonium ~icarbonate, ammonium carbamate or carba~ide. According to the lay~open print, it is also possible to use gas generatiIlg compounds which do not split the ammon;a, i.e. compounds which have been used as blowing agent in the manufacture of foamed plastic articles. It is stated that w~ are dealing with compounds which at elevat~d temperature split off nitrogen, e.g. aæodicarbonamide with several compounds. According to the lay-open print, it is also possible to use oxygen generating compounds, e.g.
carbamide peroxide adducts and finally it is also possible to use a com~ination of substances, which are thermally decomposed with gas generation.
The description discloses how the cleaning agent in question can be used: a solution in water or possibly partially a dispersion of the means being sprayed as such into the flue gas space o~ the furnacer using for this purpose a spray device commonly available on the market with su~ficient capacity, e.g. those available for spraying of gardens against harmful insects.
All of the known processes and means described above for 34~i cleaning the flue gas side of furnaces have various dis-advantages which can be avoided with the present invention.
The present invention relates to a process, according to which steam, prior to being supplied to the flue gas side for example of the ~urnace, is saturated with a com-position which, if the process is carried out in only one step, or a~ternatively in the first step of a multistep process, i.a. produces an increase in the pH value of the ]o steam to a level which is sufficient and necessary for creating a basic environment, in which the components of the composition during the cleaning process transform all harmful sulphur compounds in the coatings and environmental-ly harmful heavy metals into harmless salts which can be easily remo~ed from the bottom of the furnace. Saturating the steam with the composition in question practically completely elim;~natesthe formation of sulphuric acid with accompanying problems according to the traditional processes.
~ sulphuric acid is still formed upon contact o~ the steam with the sulphur compounds in the coatings, this acid is immediately neutralized by alkali in the composition, such as alkali hydroxide, silicates or phosphates. Normally, however, as was mentioned, other compounds are formed in the reaction between the components of the composition and the sulphur compounds, which will be discussed in more detail below.
The composition used in the process according to the inven-tion consists of a mixture, which primarily and in principle comprises synth~tic tensides, or~anic complexing agents, alkali which in addition to the aboYe mentioned effects (i.e. achieving a basic environment and neutralizing any sulphuric acid formed) also have a direct grease dissolving and cleaning effect, environmentally safe solvents and solvent vehicles, corrosion inhibitor, passivating additive, sur~actants and water. The make up of the composition is directed in each individual cleaning case to the type of s pollutants occurring and the coatings in the spaces to be cleaned and to the thickness of the coating. In practice, several steps must often be combined to achieve a satis-factory clean result. Thus it is not possible -to recommend a uniform composition for all types of furnace units and coatings.
When usiny a cleaning process in two steps for a ~urnace unit for example, the first step is suitably carried out in a basic en~ironment as mentioned above, while the second step, for remoYing for example hard to remove burned on residue on furnace walls, such as oil coke and flame soot as well as iron sulphate coatings~ is performed in an acid environment.
Thus the scope of the in~ention encompasses the use of a number of special cleaning a~ents which best fulfil the requirements. The in~ention fulfils even present hiyh environmental standards. This is especially true with regard to acid components in coatings such as sulphur compounds and harmful heavy metals such as vanadium, nickel, iron, copperr cadmium~ lead, zinc~ mercury and other metal ionsO These are neutralized and converted into harmless compounds or salts in the cleaning process in one or more steps, i.e~ before the waste products enter the drainage system. Our tests have shown that waste products from the cleaning process contain only half or one fourth of the amount of environmentally hazardous substances permissible by the environmental authorities.
The co~positions used in the process accordin~ to the invention are in the form of premixed additives, either YiScous liquids or powders, which are mixed with water be~ore u5e.
For cleanin~ and removing soot ~rom ~urnaces and removin~
coatin~s in lar~e furnace units~ a composition in liquid 3~;
form appears to be advantageous A powder composition has the advantage that it need not be protected from frost, which can be important in certain cases.
-S The process according to the invention in combination withthe special cleaning cvmpositions can be used in closed tanks for example and all types of combustion systems with fossil ~-uels ~or achie~i~ a particularly effective cleaning, soot removal and removal of coatings by means of a non-damaging treatment, which i,a. eliminates the danger ofcorrosion damage to the metal surfaces. The process is considera~ly more simple an~ less time-consuming than methods used up to now and the treatment result is decidedly better, thus providing economic advantages over traditional methods. The process according to the invention also provides an effective corrosion protection of furnace walls for example. The compositions used according to the inven-tion are environmentally safe and do not damage hands or clothings. Nor are they poisonous, thus making handling ~hereof completely safe. For bulk handling however, it is recommended that protective glasses and rubber gloves be used to prevent splashing in the eyes or lengthy skin contact. In the process according to the invention, waste products from the treatment of furnaces or tanks are collected on the bottom of the furnace or tank in the form of a slud~e. No special disposal prescriptions are required for the bottom sludge, There is no poisonous discharge and thus no separate drain cleaning or detoxification is re-quired. At the same time as the metal surface is cleaned down to the metal in the process according to the invention, materials which are normally dan~erous in normal cleaning of furnaces, are converted to harmless salts and enYiron-mentally safe xesidue. After the cleaning treatment, an anticorrosi~e surface passivatin~ layer is formed on the furnace wall, which also has the e~fect that soot will not fasten as easily to the furnace wall.
ll ~2~13~
Said anticorrosion effect and the formation of a passivating layer on the furnace wall is suitably achieved by performing the passivation in a separate step, after the primary clean-ing process~ By formation of a surface-passivating layer, the life of the furnace can be appreciably extended. The passivating layer formed on the ~urnace wall consis-ts of iron or zinc phosphate and iron oxide and has a weight of 200-lOOO~m~/m . Examples of passi~ating agents will be gi~en below.
In summary, the process according to the invention has the following characteristics for furnace cleaning:
1. The furnace is turned of~.
2. The furnace is sealed to form a closed space.
3. Steam, containin~ the cleanin~ composition, is introduced in a pressureless state to the furnace,
4. The steam splits off all coatings.
5. All coatings fall to the bottom of the furnace where they are removed.
6. The furnace is thereafter like new (cleaned down to me~
After these steps the burner is adjusted and sealing is done as needed.
~5 The process is similar when applied to other enclosed spaces than f~rnaces.
Thus in the process according to the invention, the cleaning co~position used together with water produces a steam which is then introduced in a pressureless state into the space to be cleaned~ e~g. the flue gas space of a furnace.
The steam made up of water and cleaning co~position can be made accordin~ to two different embodiments within the scope of the in~ention:
~2~3~;
A) The initially viscous or powder cleaning composition is dissolved in water of normal pH value and this aqueous solution together with other steam forming water is vapour-ized together in a device which also falls within the scope of the invention and will be described below. The mixed steam is then lntrod~1ced without pressure into the space to be cleaned, e.g. the flue gas side of a furnace.
. ~ .
.
B~ The aqueous solution of the cleaning composition is introduced into the pressureless steam already formed in the device according to the invention or provided from another source at the site tin that case being first de-pressurized1. The ~apourization temperature of the composi-tion lies sufficiently below the temperature of the steam so that vapourization of the composition takes place immediately upon introduction of the steam. The introduction of the aq~eous solution of the composition into the steam presents no problen~ since the steam is in a "pressureless state", i.e. îs at approx~mately ambient pressure. Introduc-tion can be done by means of a pump for example.
The invention will be illuminated in the following by meansof an example with reference to the accompanying drawing, which shows a furnace and a de~ice according to the inven-tion for carrying out the process according to variant A).
The furnace l is provided with a burner 2 which generatesflue gas. These rise upwards in the furnace past a hotwater heater 3 and leave the ~urnace through a flue duct 4. Unter normal operation of the urnace, soot and solid coatings 5 are formed~ which lower the efficiency of the hotwater heater 3. Also, the coatin~s increase the flue gas tempera-ture signi~icantly, which means both poor use of the fuel supply and increased wear on the flue gas ducts and chimney.
When the furnace 1 is to be cleaned of the coatings 5, the burner 2 is t~rned of~ the flue ~s damper i~ closed and 13 ~ 3~S
other openings or covers are closed and sealed. A steam unit 6 is connected via a steam line 7 to the flue gas side of the furnace.
According to the idea o~ the invention, the furnace de-scribed above can instead be another closed space which is to be cleaned of coatings on the walls.
The steam uni.t 6 is provided with a chamber 8, in which, accordiny to the embodi.ment shown, an electrode 9 is arr~nged. This part can be made d~f~erently from that shown in the drawi.ng. The heating unit can be made as immersion electrode, using process variant Bl. The composition is thus introduced in thi.s case in aqueous solution into the steam via an introduction unit (not shown~ in the steam line 7 after the vapourization chamber 8, by means of which line, the chamber is connected to the closed space, e.g. the furnace.
An inlet line 10 for water is connected to the lower end of the chamber 8. A reduction valve 11 is included in the inlet line 10, hy means: of which the water flow through the inlet line 10 can be re~ulated, The reduction valve 11 is also provid~d with a branch 12 for a feeder line 13 for the cleaning composition 14, which is stored in a container 15. The composition in liquid form, which is produced by dissolving the initially viscous or powdered composition in water, is drawn by the flow of water through the reduc-tion val~e into the cham~er 8 in the steam unit 6. Alter-nati~ely, a pump (not shown~. in the feeder line 13 can pressthe co~position into the branch 12, when a larye amount of composition is to be mixed into th.e steam.
The flow of liquid composition 14 into the inlet line 10 can be regulated by a ~alve 16. The flow of the mixture of composition 14 and water into the chamber 8 can be regulated by means (not shownl i~n the steam unit 6 for sensing the , . , ~%1~L3~S
liquid level in the chamber together with a throttle valve 17. Such a liquid level sensor de~ice should suitably be included in the device even when using immersion electrodes for heating in variant Bl.
The reduction valve 11 is provided with a nonreturn valve (not shown), which pre~ents water from penetrating into the feeder lih~ 13 for the composition, when the flow to the chamber 8 is cut off by the val~e 17.
The device can be adapted to closed spaces, e.g. furnaces of various dimensions by sett~ng the reduction valve 11 for small flows of water and composition 14 when a small space is to be cleaned, and for greater flows when a large space, e.g. an industrial f~lrnace is to be cleaned. When said setting has been ~ade, the steam formation in the unit 6 has automatically the correct admixture of cleaning composition.
The steam saturated with the composition according to the invention u~ually has, in a one step process, a pH value of between 8 and 14. The steam is condensed in a known manner on the ~etal walls o~ the flue gas side of a furnace for example. Surfactants in the composition facilitate penetra-tion of the composition into layers of soot for example andinto the solid coatings; and tensides and complexing agents in the composition break down the coatings~ Corrosion inhibitors in the cleaning composition prevent corrosion when the metal surfaces a~ter the steam treatment are rinsed clean in a known manner with plain water.
The process described according to the invention eliminates the problem of neutralizin~ the coatings removed from a furnace, for example ~y caustic soda, as is done according to the prior art. Thus the handlin~ o~ caustic soda is eliminated and thereby the risk of corrosion damage to the furnace and drainage system.
The cleaning composition used in the process according to the invention does not give rise to lime deposits in the steam unit ~ and the risk of toxic discharge into the sewage system is eliminated~, It has already been mentioned S that the process substantially reduces the treatment time for cleaning over known art. In trials for cleaniny a furnace of size 1000 Mcal, the time saved o~er ordin~ry steam cleaning was about 12 hours.
By ~irtue of the ~act that the time consumed per cleaning operation is thus reduced and the corrosion d~mage is eliminated, furnaces can be cleaned, for maintaining a high efficiency, more often than pre~iously at the same cost as previo~sly.
The adaption of the process to the type of coating to be removed As mentioned above, the process according to the invention is adapted to the nature o~ the coatings to be removed, by suitable selection of the cleaning composition. In principle, the process can be divided into for example the following reaction types;
1. Desulphurization of furnaces for example by the zinc-carbonate method, the composition being based on basic zinc carbonate ~ZnCO3), which reacts with damaging sulphur compounds in alkaline environment by forming insoluble zinc sulphide (ZnSl.
2. The sulphurization according to the iron(II~hydroxy method, the composition being based on iron(II)hydroxide (Fe(OH)2), which reacts with damaging sulphur compounds in alkaline environment while forming insoluble iron sulphide (FeS2l.
3. Desulphurization according to the iron(III~oxide method, the composition being based on colloidal magnetic iron (III)oxide (Fe3O4~, which transforms damaging sulphur compounds in alkaline environment into insoluble iron ,:i ~L2~134S
sulphide (FeS2).
4. Desulphurization according to the copper carbonate method, the composition being based on copper carbonate (CuCO31, which reacts with damaging sulphur compounds while forming insoluble coppex sulphide (CuS~.
5. Desulphurization according to the hydrogen peroxide method, the composition being based on stabilized hydrogen peroxide (~2~ sodium percarbonate (Na2CO3 -1.5 H2O2~ or percarbamide ((NH2)2CO H202) and the capac~ty o~ these compounds to completely oxidize sulphur compounds into c~mpletely harmless salts.
The following are examples of tensides which can be in-cluded in the cleanin~ composition;
Hydroxy alkyl-ethyl alkyl amino ethyl glycine, which is an amphoteric tenside, which is effecti~e in both strongly alkaline and acidic cleaning agents. It is biodegradable and non toxic.
Lauryl di~ethyl carboxymethyl ammonium betaine, which is an amphoteric tenside, which is effective and stable in both alkaline and acidic environment. It is biodegradable and non-toxic.
Alkylphenylpolyglycol ether with 10 ethylene oxide groups in the molecule which is a non-ionic tenside with especially good cleaning and emulsifying properties. It is partially biodegradable and non-to~ic.
It is also possible to use combinations of the above mentioned ~ensides, which have good ~xease, dirt and soot-3a solving properties and ~re characterized by good penetra-tion capacity into the pores, cracks and cavities of the coatings. For example combustion residue in coatings in a furnace are loosened ~ore rapidly from the metal walls.
An example of ~ co~ined corros~on inhibitor and emulsifier in the cleaning cwnposition is l--hy~roxyethyl-2-alkyl-imidazoline, which has ~ood adhesion to all types of metal ~2~L~3~
surfaces.
An example of a complexing a~ent in the composition for heavy metals in the combustion residue and coatings, such as copper, cadmium, silver, mercury, lead, nickel and several other metal ions, is ~-mercaptobenzo-1,3,5-triazine.
Other heavy ~etals in the combustion residues and coatings, such as calci~m, magnesiu~, iron, copper and several other metal ions~ form soluble complex salts with ethylene diamino-tetra acetic acid (EDTA), nitrilo-triacetate (NTA), diethylene triamino penta acetic acid (DTPE~ or hydroxy-ethyl-ethylene diamino-triacetic acid ~HEEDTE).
An example of a solvent vehicle in aqueous solutions o~ the composition is sodium cumol sulfonate, which has good dispersion properties.
An example of an environmentally safe solvent for grease and ~uel oils is 1,2-propylene glycol and iso-propanol.
Incineration o~ waste products ~rom the cleaning process As has already been mentioned, waste products from the cleaning and treatment o~ ~urnaces for example fall to the ~ottom of the furnace in the form of a slurry which is removed therefrom. To facilitate the transport of these waste products, it is possible if desired to dewater and thicken the slurry ~y adding environmentally safe high-molecular flocculents based on polyacryl amide. No specialinstructions for handlin~ the waste slurry are required and as was mentioned abo~e~ there is no toxic discharge, and therefore no separate discharge purification or detoxification is required.
The process according to the inYention can be carried out, as has been ~entioned abo~e, in one or two steps, depending , . . .
3~;
on the composition and thickness of the coatings. Below are some examples of the make up of the cleaning composition:
1. Cleaning of furnaces ~or~example by using a one step process ~ Neutralization of steam condensate and removal of soot, heavy ~eta~s and lighter coatings from furnace walls is carried out in an alkaline enYironment in a one step process by using for example the above mentioned zinc carbonate method, iron(Irlhydroxide method, iron(III~oxide method, copper carbonate method or the hydrogen peroxide method.
The followin~ cleaning agents, for example, can be used with advanta~e:
A. Stron~ly alkaline specially composed cleaning agent in liquid form, designed for neutralization of the drop water and for removing soot and li~ht coatings in furnaces, by means of which the appearance of corrosion damage on furnace walls is eliminated by e~ective desulphurization. Damaging sulphur compounds are transformed in alkaline environment by complete oxidation into entirely harmless salts which end up at the bottom of the furnace where they are removed.
The make up of the composition:
5-10 % by wei~ht hydroxy alkyl-ethyl-alkyl-amino-ethyl~
glycine (about 28 % active su~stance) 3-5 % by weight lauryl di~ethyl carboxymethyl ammonium-betaine (dimethyl lauryl aminobetaine, about 39 % activesubstance~
2-4 % by weight alkyl phenyl polyglycol ether with 10 ethylene oxide groups in the molecule, about 100 % active substancel 1~2 % by weight l-hydroxy ethyl~2-alkyl-imidazoline 2-3 % by weight 1-mercapto-benæo-1,3,5-triazine 5-10 % by wei~ht potassilDm hydroxide solution (about 40 %~
~Z~3~
5-8 % by weiyht tetra-potassium pyrophosphate 3-5 % by weight zinc carbonate, basic 2-3 % by weight iso-propanol 3-5 % by weight 1,2-propylene ylycol 1-2 ~ by weight ethylene diamine tetra-acetic acid (EDTA) The rest water ~p to 100 % by weight.
B. Stro~ alkaline cleaning agent in powder form.
A spec.~ally composed cle~ning agent in powder form designed for neutral;zation of the drop water and for removing soot and light coatings in furnaces. It provides a non-corrosive treatment of ~urnaces by e~fecti~e desulphurization of furnace walls. D~maging sulphur compounds are transformed in alkali~ne environment into comple~ely harmless salts which end up in the ~ottom of the furnacel where they are removed .
The mak.e ~p of the co~position:
10-12 ~ ~y weight triammoni~ dodecylbenzene sulfonate (about ~2 % acti~e substancel 15-20 % ~y weight sodium cumol sulfonate powder (aboutlO0 %
acti~e suhstancel 10-15 % by wei~ht trisodiu~ phosphate (tertially sodium phosphate~
8-10 % by weight sodium percarbonate (Na2CO3 1.5 H2O) 2-8 ~ by weight sodi~m hydro~ide in powder form, water-free 35-40 % ~y weight sodium disilicate powder ("sodiumsilicate powder"
1~2 % by wei~ht ethylene diamine tetra-acetic acid (EDTA~
The rest water up to 100 % by wei~ht.
C. Ne~tral cleaning a~ent in powder form.
This composition is used when;the nature of the coatings do not require an especially stron~ alkaline cleaning agent in liguid or powder for~.
The ~ake up of the co~position;
.
~ L3~S
10-12 ~ by weight triammonium dodecylbenzene sulfonate (about 92 % acti~e substance~
35-50 % by weight sodi~m tripolyphosphate in the form of water-free powder
After these steps the burner is adjusted and sealing is done as needed.
~5 The process is similar when applied to other enclosed spaces than f~rnaces.
Thus in the process according to the invention, the cleaning co~position used together with water produces a steam which is then introduced in a pressureless state into the space to be cleaned~ e~g. the flue gas space of a furnace.
The steam made up of water and cleaning co~position can be made accordin~ to two different embodiments within the scope of the in~ention:
~2~3~;
A) The initially viscous or powder cleaning composition is dissolved in water of normal pH value and this aqueous solution together with other steam forming water is vapour-ized together in a device which also falls within the scope of the invention and will be described below. The mixed steam is then lntrod~1ced without pressure into the space to be cleaned, e.g. the flue gas side of a furnace.
. ~ .
.
B~ The aqueous solution of the cleaning composition is introduced into the pressureless steam already formed in the device according to the invention or provided from another source at the site tin that case being first de-pressurized1. The ~apourization temperature of the composi-tion lies sufficiently below the temperature of the steam so that vapourization of the composition takes place immediately upon introduction of the steam. The introduction of the aq~eous solution of the composition into the steam presents no problen~ since the steam is in a "pressureless state", i.e. îs at approx~mately ambient pressure. Introduc-tion can be done by means of a pump for example.
The invention will be illuminated in the following by meansof an example with reference to the accompanying drawing, which shows a furnace and a de~ice according to the inven-tion for carrying out the process according to variant A).
The furnace l is provided with a burner 2 which generatesflue gas. These rise upwards in the furnace past a hotwater heater 3 and leave the ~urnace through a flue duct 4. Unter normal operation of the urnace, soot and solid coatings 5 are formed~ which lower the efficiency of the hotwater heater 3. Also, the coatin~s increase the flue gas tempera-ture signi~icantly, which means both poor use of the fuel supply and increased wear on the flue gas ducts and chimney.
When the furnace 1 is to be cleaned of the coatings 5, the burner 2 is t~rned of~ the flue ~s damper i~ closed and 13 ~ 3~S
other openings or covers are closed and sealed. A steam unit 6 is connected via a steam line 7 to the flue gas side of the furnace.
According to the idea o~ the invention, the furnace de-scribed above can instead be another closed space which is to be cleaned of coatings on the walls.
The steam uni.t 6 is provided with a chamber 8, in which, accordiny to the embodi.ment shown, an electrode 9 is arr~nged. This part can be made d~f~erently from that shown in the drawi.ng. The heating unit can be made as immersion electrode, using process variant Bl. The composition is thus introduced in thi.s case in aqueous solution into the steam via an introduction unit (not shown~ in the steam line 7 after the vapourization chamber 8, by means of which line, the chamber is connected to the closed space, e.g. the furnace.
An inlet line 10 for water is connected to the lower end of the chamber 8. A reduction valve 11 is included in the inlet line 10, hy means: of which the water flow through the inlet line 10 can be re~ulated, The reduction valve 11 is also provid~d with a branch 12 for a feeder line 13 for the cleaning composition 14, which is stored in a container 15. The composition in liquid form, which is produced by dissolving the initially viscous or powdered composition in water, is drawn by the flow of water through the reduc-tion val~e into the cham~er 8 in the steam unit 6. Alter-nati~ely, a pump (not shown~. in the feeder line 13 can pressthe co~position into the branch 12, when a larye amount of composition is to be mixed into th.e steam.
The flow of liquid composition 14 into the inlet line 10 can be regulated by a ~alve 16. The flow of the mixture of composition 14 and water into the chamber 8 can be regulated by means (not shownl i~n the steam unit 6 for sensing the , . , ~%1~L3~S
liquid level in the chamber together with a throttle valve 17. Such a liquid level sensor de~ice should suitably be included in the device even when using immersion electrodes for heating in variant Bl.
The reduction valve 11 is provided with a nonreturn valve (not shown), which pre~ents water from penetrating into the feeder lih~ 13 for the composition, when the flow to the chamber 8 is cut off by the val~e 17.
The device can be adapted to closed spaces, e.g. furnaces of various dimensions by sett~ng the reduction valve 11 for small flows of water and composition 14 when a small space is to be cleaned, and for greater flows when a large space, e.g. an industrial f~lrnace is to be cleaned. When said setting has been ~ade, the steam formation in the unit 6 has automatically the correct admixture of cleaning composition.
The steam saturated with the composition according to the invention u~ually has, in a one step process, a pH value of between 8 and 14. The steam is condensed in a known manner on the ~etal walls o~ the flue gas side of a furnace for example. Surfactants in the composition facilitate penetra-tion of the composition into layers of soot for example andinto the solid coatings; and tensides and complexing agents in the composition break down the coatings~ Corrosion inhibitors in the cleaning composition prevent corrosion when the metal surfaces a~ter the steam treatment are rinsed clean in a known manner with plain water.
The process described according to the invention eliminates the problem of neutralizin~ the coatings removed from a furnace, for example ~y caustic soda, as is done according to the prior art. Thus the handlin~ o~ caustic soda is eliminated and thereby the risk of corrosion damage to the furnace and drainage system.
The cleaning composition used in the process according to the invention does not give rise to lime deposits in the steam unit ~ and the risk of toxic discharge into the sewage system is eliminated~, It has already been mentioned S that the process substantially reduces the treatment time for cleaning over known art. In trials for cleaniny a furnace of size 1000 Mcal, the time saved o~er ordin~ry steam cleaning was about 12 hours.
By ~irtue of the ~act that the time consumed per cleaning operation is thus reduced and the corrosion d~mage is eliminated, furnaces can be cleaned, for maintaining a high efficiency, more often than pre~iously at the same cost as previo~sly.
The adaption of the process to the type of coating to be removed As mentioned above, the process according to the invention is adapted to the nature o~ the coatings to be removed, by suitable selection of the cleaning composition. In principle, the process can be divided into for example the following reaction types;
1. Desulphurization of furnaces for example by the zinc-carbonate method, the composition being based on basic zinc carbonate ~ZnCO3), which reacts with damaging sulphur compounds in alkaline environment by forming insoluble zinc sulphide (ZnSl.
2. The sulphurization according to the iron(II~hydroxy method, the composition being based on iron(II)hydroxide (Fe(OH)2), which reacts with damaging sulphur compounds in alkaline environment while forming insoluble iron sulphide (FeS2l.
3. Desulphurization according to the iron(III~oxide method, the composition being based on colloidal magnetic iron (III)oxide (Fe3O4~, which transforms damaging sulphur compounds in alkaline environment into insoluble iron ,:i ~L2~134S
sulphide (FeS2).
4. Desulphurization according to the copper carbonate method, the composition being based on copper carbonate (CuCO31, which reacts with damaging sulphur compounds while forming insoluble coppex sulphide (CuS~.
5. Desulphurization according to the hydrogen peroxide method, the composition being based on stabilized hydrogen peroxide (~2~ sodium percarbonate (Na2CO3 -1.5 H2O2~ or percarbamide ((NH2)2CO H202) and the capac~ty o~ these compounds to completely oxidize sulphur compounds into c~mpletely harmless salts.
The following are examples of tensides which can be in-cluded in the cleanin~ composition;
Hydroxy alkyl-ethyl alkyl amino ethyl glycine, which is an amphoteric tenside, which is effecti~e in both strongly alkaline and acidic cleaning agents. It is biodegradable and non toxic.
Lauryl di~ethyl carboxymethyl ammonium betaine, which is an amphoteric tenside, which is effective and stable in both alkaline and acidic environment. It is biodegradable and non-toxic.
Alkylphenylpolyglycol ether with 10 ethylene oxide groups in the molecule which is a non-ionic tenside with especially good cleaning and emulsifying properties. It is partially biodegradable and non-to~ic.
It is also possible to use combinations of the above mentioned ~ensides, which have good ~xease, dirt and soot-3a solving properties and ~re characterized by good penetra-tion capacity into the pores, cracks and cavities of the coatings. For example combustion residue in coatings in a furnace are loosened ~ore rapidly from the metal walls.
An example of ~ co~ined corros~on inhibitor and emulsifier in the cleaning cwnposition is l--hy~roxyethyl-2-alkyl-imidazoline, which has ~ood adhesion to all types of metal ~2~L~3~
surfaces.
An example of a complexing a~ent in the composition for heavy metals in the combustion residue and coatings, such as copper, cadmium, silver, mercury, lead, nickel and several other metal ions, is ~-mercaptobenzo-1,3,5-triazine.
Other heavy ~etals in the combustion residues and coatings, such as calci~m, magnesiu~, iron, copper and several other metal ions~ form soluble complex salts with ethylene diamino-tetra acetic acid (EDTA), nitrilo-triacetate (NTA), diethylene triamino penta acetic acid (DTPE~ or hydroxy-ethyl-ethylene diamino-triacetic acid ~HEEDTE).
An example of a solvent vehicle in aqueous solutions o~ the composition is sodium cumol sulfonate, which has good dispersion properties.
An example of an environmentally safe solvent for grease and ~uel oils is 1,2-propylene glycol and iso-propanol.
Incineration o~ waste products ~rom the cleaning process As has already been mentioned, waste products from the cleaning and treatment o~ ~urnaces for example fall to the ~ottom of the furnace in the form of a slurry which is removed therefrom. To facilitate the transport of these waste products, it is possible if desired to dewater and thicken the slurry ~y adding environmentally safe high-molecular flocculents based on polyacryl amide. No specialinstructions for handlin~ the waste slurry are required and as was mentioned abo~e~ there is no toxic discharge, and therefore no separate discharge purification or detoxification is required.
The process according to the inYention can be carried out, as has been ~entioned abo~e, in one or two steps, depending , . . .
3~;
on the composition and thickness of the coatings. Below are some examples of the make up of the cleaning composition:
1. Cleaning of furnaces ~or~example by using a one step process ~ Neutralization of steam condensate and removal of soot, heavy ~eta~s and lighter coatings from furnace walls is carried out in an alkaline enYironment in a one step process by using for example the above mentioned zinc carbonate method, iron(Irlhydroxide method, iron(III~oxide method, copper carbonate method or the hydrogen peroxide method.
The followin~ cleaning agents, for example, can be used with advanta~e:
A. Stron~ly alkaline specially composed cleaning agent in liquid form, designed for neutralization of the drop water and for removing soot and li~ht coatings in furnaces, by means of which the appearance of corrosion damage on furnace walls is eliminated by e~ective desulphurization. Damaging sulphur compounds are transformed in alkaline environment by complete oxidation into entirely harmless salts which end up at the bottom of the furnace where they are removed.
The make up of the composition:
5-10 % by wei~ht hydroxy alkyl-ethyl-alkyl-amino-ethyl~
glycine (about 28 % active su~stance) 3-5 % by weight lauryl di~ethyl carboxymethyl ammonium-betaine (dimethyl lauryl aminobetaine, about 39 % activesubstance~
2-4 % by weight alkyl phenyl polyglycol ether with 10 ethylene oxide groups in the molecule, about 100 % active substancel 1~2 % by weight l-hydroxy ethyl~2-alkyl-imidazoline 2-3 % by weight 1-mercapto-benæo-1,3,5-triazine 5-10 % by wei~ht potassilDm hydroxide solution (about 40 %~
~Z~3~
5-8 % by weiyht tetra-potassium pyrophosphate 3-5 % by weight zinc carbonate, basic 2-3 % by weight iso-propanol 3-5 % by weight 1,2-propylene ylycol 1-2 ~ by weight ethylene diamine tetra-acetic acid (EDTA) The rest water ~p to 100 % by weight.
B. Stro~ alkaline cleaning agent in powder form.
A spec.~ally composed cle~ning agent in powder form designed for neutral;zation of the drop water and for removing soot and light coatings in furnaces. It provides a non-corrosive treatment of ~urnaces by e~fecti~e desulphurization of furnace walls. D~maging sulphur compounds are transformed in alkali~ne environment into comple~ely harmless salts which end up in the ~ottom of the furnacel where they are removed .
The mak.e ~p of the co~position:
10-12 ~ ~y weight triammoni~ dodecylbenzene sulfonate (about ~2 % acti~e substancel 15-20 % ~y weight sodium cumol sulfonate powder (aboutlO0 %
acti~e suhstancel 10-15 % by wei~ht trisodiu~ phosphate (tertially sodium phosphate~
8-10 % by weight sodium percarbonate (Na2CO3 1.5 H2O) 2-8 ~ by weight sodi~m hydro~ide in powder form, water-free 35-40 % ~y weight sodium disilicate powder ("sodiumsilicate powder"
1~2 % by wei~ht ethylene diamine tetra-acetic acid (EDTA~
The rest water up to 100 % by wei~ht.
C. Ne~tral cleaning a~ent in powder form.
This composition is used when;the nature of the coatings do not require an especially stron~ alkaline cleaning agent in liguid or powder for~.
The ~ake up of the co~position;
.
~ L3~S
10-12 ~ by weight triammonium dodecylbenzene sulfonate (about 92 % acti~e substance~
35-50 % by weight sodi~m tripolyphosphate in the form of water-free powder
7-10 % by weight sodium ~l~conate 20-25 % by weight tetrapotassium pyrophosphate
8~10 % ~y wei~ht percarbamide (NH2~2C0 F~202 The rest water up to 100 % by weight.
2. Cleanin~ by use~of a *wo step process Cleaning and remo~al of strongly adhering combustion residue for example on furnace wall.s, such as oil coke and flame soot as well as iron-sulphate coatings of a thickness of 10 ~m on furnace walls or in other enclosed spaces is suit-ably done in two steps, the first of which is carried out in an alkaline environment usin~ the above mentioned means ~or example, the second supplementary step for remoYing the strongly adhering coatin~s being carried out in an acid environment. The cleaning steps are then suitably followed by a passivation step for the ~etal surface.
The ~ollowing cleaning agents, for example, can be used with advantage:
D. Acidic cleanin~ a~ent in liquid form.
Composite cleaning agent in liquid form for removing iron sulphate, rust, soot and other coatings in furnaces for example.
The make up of the composition;
12 % by wei:ght mono~ethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P205~
12 % by weight dimethyl phosporic acid ester (short-chain phosphoric acid ester with about 64 % P205) 20 % by wei~ht ortho-phosphoric aci.d, about 85 %
15 % by weight alkylarylsulphonate 21 ~113~
8 ~ by weight alkyl phenyl polyglycolether with 10 ethylene-oxide groups in the molecule 3 % by weight coconut fatty acid amide polyglycolether with 4.5 ethylene oxide groups in the molecule 2 % by weight ethylene diaminotetra-acetic acid (EDTA-BVT), iron(III~complexing agent 2 % by weight diethylene glycol The rest w~ter up to 100 % by weight.
Passivation of the metal surfaces after cleaning was achieved with the following agents for example:
E. Alkaline passivating agents.
10 % by weight hydroxy alkyl-ethyl-alkyl-amino-ethyl-glycine (about 28 % acti~e substance~
5 % by weight alkylphenyl polyglycolether with 10 ethylene oxide groups in the molecule (about 100 % active substance) 25 % by weight sodium phosphonate 5 % by weight activator AD
10 ~ by weight potassi~m hydroxide solution, about 40 %
3 % by weight iso-propanol 5 % by weight 1,2-propylene glycol The rest water up to 100 % by weight.
F. Acidic passivating agents.
12 % by wei~ht monomethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P205~
12 % by weight dimethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P20 20 % by weight phosphoric acid 5 % by weight acti~ator SD
15 ~ by weight alkylaryl sulphonate 8 % by weight alkylphenyl polyglycolether with 10 ethylene oxide groups in the molecule 5 % by weight alpha~olefine sulphonate 2 % by weight diethylene glycol The rest water up to 100 ~ by weight.
2. Cleanin~ by use~of a *wo step process Cleaning and remo~al of strongly adhering combustion residue for example on furnace wall.s, such as oil coke and flame soot as well as iron-sulphate coatings of a thickness of 10 ~m on furnace walls or in other enclosed spaces is suit-ably done in two steps, the first of which is carried out in an alkaline environment usin~ the above mentioned means ~or example, the second supplementary step for remoYing the strongly adhering coatin~s being carried out in an acid environment. The cleaning steps are then suitably followed by a passivation step for the ~etal surface.
The ~ollowing cleaning agents, for example, can be used with advantage:
D. Acidic cleanin~ a~ent in liquid form.
Composite cleaning agent in liquid form for removing iron sulphate, rust, soot and other coatings in furnaces for example.
The make up of the composition;
12 % by wei:ght mono~ethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P205~
12 % by weight dimethyl phosporic acid ester (short-chain phosphoric acid ester with about 64 % P205) 20 % by wei~ht ortho-phosphoric aci.d, about 85 %
15 % by weight alkylarylsulphonate 21 ~113~
8 ~ by weight alkyl phenyl polyglycolether with 10 ethylene-oxide groups in the molecule 3 % by weight coconut fatty acid amide polyglycolether with 4.5 ethylene oxide groups in the molecule 2 % by weight ethylene diaminotetra-acetic acid (EDTA-BVT), iron(III~complexing agent 2 % by weight diethylene glycol The rest w~ter up to 100 % by weight.
Passivation of the metal surfaces after cleaning was achieved with the following agents for example:
E. Alkaline passivating agents.
10 % by weight hydroxy alkyl-ethyl-alkyl-amino-ethyl-glycine (about 28 % acti~e substance~
5 % by weight alkylphenyl polyglycolether with 10 ethylene oxide groups in the molecule (about 100 % active substance) 25 % by weight sodium phosphonate 5 % by weight activator AD
10 ~ by weight potassi~m hydroxide solution, about 40 %
3 % by weight iso-propanol 5 % by weight 1,2-propylene glycol The rest water up to 100 % by weight.
F. Acidic passivating agents.
12 % by wei~ht monomethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P205~
12 % by weight dimethyl phosphoric acid ester (short-chain phosphoric acid ester with about 64 % P20 20 % by weight phosphoric acid 5 % by weight acti~ator SD
15 ~ by weight alkylaryl sulphonate 8 % by weight alkylphenyl polyglycolether with 10 ethylene oxide groups in the molecule 5 % by weight alpha~olefine sulphonate 2 % by weight diethylene glycol The rest water up to 100 ~ by weight.
Claims (18)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for loosening and removing soot and solid coatings on metal surfaces in enclosed spaces by introduction of steam into the enclosed space, characterized in that the steam, before being introduced into the enclosed space, is saturated with an aqueous composition, which includes synthetic tensides, alkali, silicates and phosphates, complexing agents, environmentally safe solvent and solvent vehicle, a corrosion inhibitor to prevent corrosion on the metal surfaces when they are rinsed with plain water after the introduction of steam into the enclosed space, said process being carried out in one or more cleaning steps, the one or the last one of said cleaning steps being followed by a surface passivating step for the cleaned surfaces involving supplying a passivating agent thereto which counter-acts the continued coating of the metal surfaces.
2. Process according to claim 1, characterised in that the step of saturating the steam with the composition is achieved by supplying an aqueous solution of the compos-ition to the water for vapourization and is vapourized together therewith in a steam generating chamber within a steam unit, whereafter the steam of water and composition is introduced via a common steam conduit in a pressureless state into the enclosed space.
3. Process according to claim 2, characterized in that the enclosed space is a flue gas side of a furnace.
4. Process according to claim 1, characterized in that the step of saturating the steam with the composition is achieved by introducing an aqueous solution of the composition into the steam which is already at approximately ambient pressure, whereby the aqueous composition is vapourized and the mixed steam is thereafter introduced in a pressureless state into the enclosed space.
5. Process according to claim 4, characterized in that the enclosed space is a flue gas side of a furnace.
6. Process according to one of claims 1, 2 or 3, characterized in that the cleaning portion of the process is carried out in one step in an alkaline environment, prior to the passivating step.
7. Process according to claims 1, 2 or 3, character-ized in that the cleaning portion of the process is carried out in two steps, the first being in an alkaline environment and the other in an acidic environment, prior to the passivating step.
8. A process according to claim 4 or claim 5, carried out in a device comprising a vessel for a liquid composition, said vessel being connected via a line to a reduction valve, through which water flows to a steam generating chamber, which contains means for vapourizing the water in conjunction with said composition, the feeder line being provided with a valve for regulating the flow of the composition into a common line for the water and composition to the steam generating chamber, said steam unit comprising means for sensing the liquid level in the chamber for regulating the flow of the mixture of composition and water to the steam unit, said reduction valve being provided with a non-return valve to prevent water from penetrating into the feeder line for composition when the flow to the steam generating chamber is cut off by a valve disposed in the line.
9. A process according to claim 4 or claim 5, characterized in that the cleaning portion of the process is carried out in two steps, the first being in an alkaline environment and the other in an acidic invironment, prior to the passivating step.
10. The process as claimed in claim 1, wherein the alkali is alkali hydroxide.
11. Process for loosening and removing soot and solid coatings on surfaces in an enclosed space comprising the steps of: saturating steam with an aqueous composition including synthetic tensides, alkali, complexing agents, solvent, and a corrosion inhibitor; introducing the saturated steam solely by diffusion at approximately ambient pressure into the enclosed space; and subsequently supplying a passivating agent thereto which counteracts the continued coating of the said surface by soot and solid coatings and provide a layer including iron oxide on said surface.
12. Process according to claim 11, wherein the step of saturating the steam with the composition is achieved by supplying an aqueous solution of the composition to the water for vapourization and is vapourized together therewith in a steam generating chamber within a steam unit.
13. Process according to claim 12, wherein the enclosed space is a flue gas side of a furnace.
14. Process according to claim 11, wherein the step of saturating the steam with the composition is achieved by introducing an aqueous solution of the composition into the steam which is already at approximately ambient pressure, whereby the aqueous composition is vaporized.
15. Process according to claim 14, wherein the enclosed space is a flue gas side of a furnace.
16. Process according to one of claims 11, 12 or 13 wherein the cleaning portion of the process is carried out in one step in an alkaline environment, prior to the passivating step.
17. Process according to one of claims 11, 12 or 13 wherein the cleaning portion of the process is carried out in two steps, the first being in an alkaline environment and the other in an acidic environment, prior to the passivating step.
18. Apparatus for carrying out a process for loosen-ing and removing soot and solid coatings on surfaces in enclosed spaces, characterized in that it comprises a vessel for a liquid composition, said vessel being connected via a line to a reduction valve, through which water flows to a stream generating chamber, which contains means for vapourizing the water in conjunction with said composition, the feeder line being provided with a valve for regulating the flow of the composition into a common line for the water and composition to the steam generating chamber, said steam unit comprising means for sensing the liquid level in the chamber for regulating the flow of the mixture of composition and water to the steam unit, said reduction valve being provided with a non-return valve to prevent water from penetrating into the feeder line for composition when the flow to the steam generating chamber is cut off by a valve disposed in the line.
....
....
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8103177-5 | 1981-05-20 | ||
| SE8103177A SE437032B (en) | 1981-05-20 | 1981-05-20 | PROCEDURE AND DEVICE FOR DISPOSAL AND REMOVAL OF FIXED COATINGS ON THE SURFACE OF A HEAT OR STEAM PAN |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1211345A true CA1211345A (en) | 1986-09-16 |
Family
ID=20343881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000402177A Expired CA1211345A (en) | 1981-05-20 | 1982-05-03 | Process and device for loosening and removing solid coatings on the surfaces of enclosed spaces, e.g. the flue gas side of a furnace or boiler |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0079338B1 (en) |
| CA (1) | CA1211345A (en) |
| DE (1) | DE3264872D1 (en) |
| DK (1) | DK156677C (en) |
| FI (1) | FI75594C (en) |
| SE (2) | SE437032B (en) |
| WO (1) | WO1982004065A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE8401844A0 (en) * | 1984-04-03 | 1985-10-04 | Andren Sven Uno | boiler Sweeping |
| US6089955A (en) * | 1994-10-12 | 2000-07-18 | Nextec, Inc. | Method and composition for removing coatings which contain hazardous elements |
| FR2749855B1 (en) * | 1996-10-10 | 1998-10-30 | Eurexim | SOLID FUEL AGENT FOR DESTRUCTION OF SOOT AND TARS, MANUFACTURING METHOD THEREOF AND USE THEREOF |
| CN109675849A (en) * | 2018-11-27 | 2019-04-26 | 大唐湘潭发电有限责任公司 | A kind of black dirt of power plant's low-temperature flue gas processing system adds buck rinse-system |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2704523A (en) * | 1955-03-22 | F walters | ||
| SE166121C1 (en) * | ||||
| DE1095441B (en) * | 1954-12-10 | 1960-12-22 | Kaminfegermeister Verband Base | Process for the treatment of the inner surfaces of brick chimneys in order to remove combustion residues |
| DE1546151A1 (en) * | 1965-03-22 | 1969-05-14 | Collardin Gmbh Gerhard | Process for cleaning heating surfaces of circulating regenerative preheaters |
| NL132465C (en) * | 1967-11-24 | |||
| DE1601299A1 (en) * | 1968-01-19 | 1970-07-23 | Hutter Kg S | Method and device for cleaning flue gas exposed areas in steam boilers, heat exchangers and the like. |
| DE2702716C2 (en) * | 1977-01-24 | 1979-06-28 | Josef Krammer Chem. Dampfkessel- Reinigung, 4040 Neuss | Process and device for cleaning boilers or ovens on the smoke side |
-
1981
- 1981-05-20 SE SE8103177A patent/SE437032B/en not_active IP Right Cessation
- 1981-10-27 SE SE8106333A patent/SE8106333L/en not_active Application Discontinuation
-
1982
- 1982-04-19 WO PCT/SE1982/000125 patent/WO1982004065A1/en active IP Right Grant
- 1982-04-19 DE DE8282901377T patent/DE3264872D1/en not_active Expired
- 1982-04-19 EP EP19820901377 patent/EP0079338B1/en not_active Expired
- 1982-05-03 CA CA000402177A patent/CA1211345A/en not_active Expired
-
1983
- 1983-01-13 DK DK011583A patent/DK156677C/en active
- 1983-01-17 FI FI830144A patent/FI75594C/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FI75594B (en) | 1988-03-31 |
| EP0079338A1 (en) | 1983-05-25 |
| WO1982004065A1 (en) | 1982-11-25 |
| FI830144A0 (en) | 1983-01-17 |
| DK11583A (en) | 1983-01-13 |
| SE8106333L (en) | 1982-11-21 |
| SE8103177L (en) | 1982-11-21 |
| DK156677C (en) | 1990-02-05 |
| DE3264872D1 (en) | 1985-08-29 |
| FI830144L (en) | 1983-01-17 |
| FI75594C (en) | 1988-07-11 |
| EP0079338B1 (en) | 1985-07-24 |
| DK11583D0 (en) | 1983-01-13 |
| DK156677B (en) | 1989-09-18 |
| SE437032B (en) | 1985-02-04 |
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