Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M175/00—Working-up used lubricants to recover useful products ; Cleaning
  • C10M175/0016—Working-up used lubricants to recover useful products ; Cleaning with the use of chemical agents
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M175/00—Working-up used lubricants to recover useful products ; Cleaning
  • C10M175/0091—Treatment of oils in a continuous lubricating circuit (e.g. motor oil system)
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M175/00—Working-up used lubricants to recover useful products ; Cleaning
  • C10M175/0058—Working-up used lubricants to recover useful products ; Cleaning by filtration and centrifugation processes; apparatus therefor

Definitions

• the invention relates to a method defined in the preamble of claim 1 and to an apparatus defined in the preamble of claim 7 for deacidifying a lubricating oil mixture in the field of chemical forest industry, and to the use defined in claim 16.
• pulp is bleached in general by sodium dithionite.
• the bleaching reaction produces sulfuric acid and sulfur dioxide which are transferred with air flows e.g. from between shafts and their seals to bearings and further into oil tanks and bind to the water present in the oil, causing a decrease in the pH level.
• Sulfur dioxide is liable to be converted into sulfuric acid in the oil systems.
• hydrochloric acid may also be formed in the oil if the water present in the oil includes chlorides. Chlorides react with sulfur dioxide, producing hydrochloric acid.
• the pH of process waters is adjusted using both of the above-mentioned acids which may be transferred into lubricating oil systems.
• sulfuric acid may also be formed as a result of hydrolysis of anti-pressure and -wear additives in the oil.
• the sulfuric and hydrochloric acids as referred to are very problematic from a corrosion point of vie .
• the objective of the invention is to disclose a new and effective method and apparatus to deacidify circulating lubricating and hydraulic oils in the chemical forest industry, e.g. paper and paperboard industry.
• the invention is based on a method for dea- cidifying a lubricating oil mixture.
• the lubricating oil mixture that contains acid is conducted, preferably as a process side stream, at a temperature of less than 60 °C into a neutralization reactor, the lubricating oil mixture is brought into contact with calcium carbonate and the acid in the lubricating oil mixture is allowed to react with calcium carbonate, producing as a result of the reaction calcium compounds, carbon dioxide and water.
• the resulting calcium compounds are preferably discharged from the process.
• the resulting carbon dioxide and/or water can be discharged from the process or conducted with the lubricating oil mixture back to the process.
• the invention is based on an apparatus for deacidifying a lubricating oil mixture.
• the apparatus includes a neutralization reactor into which the lubricating oil mix- ture that contains acid is conducted at a temperature of less than 60 °C, and the neutralization reactor includes a layer that contains calcium carbonate and through which the lubricating oil mixture is conducted, so that the acid in the lubricating oil mixture reacts with cal ⁇ cium carbonate, forming calcium compounds, carbon dioxide and water.
• the apparatus includes first temperature adjustment means for adjusting the temperature of the lubricating oil mixture to less than 60 °C before conducting it into the neutralization reactor.
• the apparatus includes means, e.g. delivery piping and/or a pump, for conducting the lubricating oil mixture into the neutralization reactor and means, e.g. piping, for conducting the lubricating oil mixture out from the neutralization reactor.
• the lubricating oil mixture contains lubricating oil, and it may contain a variable quantity of water. In practice, the lubricating oil mixture always contains water. Further, in this connection the lubri- eating oil mixture contains acid, e.g. sulfuric acid or hydrochloric acid. Alternatively, the lubricating oil mixture may also contain other components, such as additives, impurities or suchlike components.
• the acid is mainly mixed in water in the lubricating oil mix- ture. The acid may be mixed in free and/or dissolved water present in the lubricating oil mixture. Prefera ⁇ bly, the acid is dissolved in the water in the lubricating oil mixture.
• the lubricating oil means in this connection any lubricating oil, hydraulic oil or lub- ricant or different mixtures thereof which can be used in the lubricating systems in chemical forest industry.
• the lubricating oil is selected from the circulation lubricating oil, hydraulic oil and mixtures thereof.
• the acid in the lubricating oil mixture is sulfuric acid (H 2 S0 4 )
• the calcium compound formed in the reaction with calcium carbonate is calcium sulfate (CaS0 4 ) .
• the acid in the lubricat ⁇ ing oil mixture is hydrochloric acid (HCl) , in which case the calcium compound formed in the reaction with calcium carbonate is calcium chloride (CaCl 2 ) .
• the chemical forest industry means in this connection the industry that processes wood. This industry is considered to include the paper and paper- board industry, chemical pulp industry, groundwood mills and refiner mechanical pulp mills.
• the manufacture of paper means in this con ⁇ nection the making of any paper product that may have been formed from any suitable raw material.
• the manu- facture of paperboard means in this connection the making of any paperboard product that may have been formed from any suitable raw material.
• the paper and paperboard product may have been formed from chemical pulp, mechanical pulp, recycled pulp, fibrous pulp, other suitable pulp used in the paper and paperboard industry or different combinations thereof.
• the paper and paperboard product may in this connection mean any web-type or sheet-type and shaped product.
• the lubricating oil mix- ture is conducted from a lubricating oil tank, such as circulation lubricating or hydraulic oil tank, into the neutralization reactor.
• a lubricating oil tank such as circulation lubricating or hydraulic oil tank
• the pu ⁇ rified lubricating oil mixture is conducted from the neutralization reactor back into the lubricating oil tank or a part thereof or another lubricating oil tank, e.g. by means of piping and/or a pump.
• the apparatus includes at least one tank for the lubricating oil mixture.
• the apparatus includes se- cond temperature adjustment means for adjusting the temperature of the lubricating oil mixture after the neu- tralization reactor when the lubricating oil mixture has been conducted out from the neutralization reactor.
• the apparatus includes at least one heat exchanger. In one embodiment, the heat exchanger is provided before the neutralization reactor for cooling the lubricating oil mixture. In one embodiment, the heat exchanger is provided after the neutralization reactor for heating the lubricating oil mixture. In one embodiment, the apparatus includes at least two heat exchangers, at least one of which is provided before the neutralization reactor and at least one after the neutralization reactor.
• the resulting calcium compound is separated from the lubricating oil mixture, and preferably the lubricating oil mixture is returned into the lubricating oil tank or a part thereof or conducted into another lubricating oil tank.
• the resulting calcium compound is present in a solid state after the neutralization reactor.
• the resulting calcium compound is dissolved in water in the lubricating oil mixture after the neutralization reactor.
• the resulting calcium compound is converted into a crystalline form after the neutralization reactor.
• the calcium compound is calcium sulfate, i.e. gypsum (CaS0 4 ) .
• the calcium compound is calcium chloride (CaCl 2 ) .
• the apparatus includes at least one mechanical filter, preferably for removing solid impurities by filtration.
• the mechanical filter is provided after the neutralization reactor and before the lubricating oil tank for removing or reducing desired components from the purified lubricating oil mixture.
• the calci- um compound, e.g. calcium sulfate is separated by means of the mechanical filter.
• the apparatus includes a vacuum distillator. The vacuum distillator is used preferably in the event that the lubricating oil mixture contains a chloride compound, e.g. calcium chlo- ride, after the neutralization reactor. By means of the vacuum distillator, the calcium compound formed in the neutralization reactor can be converted into a crystalline form. In one embodiment, the vacuum distillator can be used to crystallize the calcium chlo- ride.
• the lubricating oil mixture is conducted through the mechanical filter and then preferably returned into the lubricating oil tank.
• the flow of the lubricat- ing oil mixture is provided in the neutralization reactor from below upwards.
• the temperature of the lubricating oil mixture conducted into the neutralization reactor is less than 40 °C, in one embodiment from 10 to 30 "C and in one embodiment from 15 to 25 °C.
• the reaction time, e.g. residence time, of the lubricating oil mixture with calcium carbonate is less than 25min, and in one embodiment less than lOmin.
• the neutralization reactor is sized and/or delivery of the lubricating oil mixture is provided such that the reaction time of the lubricating oil mixture with calcium carbonate reaches a desired level in the neutralization reactor.
• calcium carbonate is mainly present in the form of granules of a granule size from 1 to 16 mm, in one embodiment from 1 to 10 mm.
• the apparatus includes at least one pressure measurement device for determining the pressure difference of the calcium carbonate layer in the neutralization reactor.
• the measurement device may include one or more measurement sensors or measurement elements.
• the calcium carbonate layer means in this connection any layer, bed or the like which is provided in the neutralization reactor, which contains calcium carbonate and through which the lubricating oil mixture is conducted.
• the calcium carbonate layer is supported by a supporting mesh which may be formed from a suitable polymer, engineering plastic, acid-proof steel or other suitable material that is stable toward acids.
• the calcium carbonate layer is provided within an enclosed structure, e.g. cartridge, capsule or suchlike enclosed structure, through which flow of the lubricating oil mixture is conducted in the neutralization reactor.
• the enclosed structure such as cartridge, capsule or the like, can be easily replaced, for example in case the pressure difference should rise too high .
• the neutralization reactor is divided into separate sections and a layer, such as bed, that contains calcium carbonate is provided in these different sections in such a way that each section contains a layer that contains calcium carbonate, and the lubricating oil mixture is arranged to be conducted through these sections in a sequential or parallel manner.
• a layer that contains calcium carbonate is provided within an enclosed structure in each section.
• the apparatus includes an adjustment system for following the carbon dioxide content and adjusting it to a level of less " than 20mg/l in the neutralization reactor.
• the adjustment system includes at least one sensor for following the carbon dioxide level.
• the adjustment system includes control means for adjusting conditions in the neutralization reactor, such as for lowering the carbon dioxide level.
• the method and apparatus according to the invention can be used in the field of chemical forest industry.
• the method and apparatus according to the invention can be used in connection with a lubricating system, such as in connection with a circulation lubricating and hydraulic system, in the paper and pa- perboard industry in particular when the pH of water in the lubricating oil mixture starts to decrease, e.g. below the pH level of 4.5.
• a lubricating system such as in connection with a circulation lubricating and hydraulic system
• the pH level of water in the lubricating oil mixture starts to decrease, e.g. below the pH level of 4.5.
• the method is used when the pH level of the water is less than 4.5.
• the method and apparatus can be used in connection with lubricating oil side stream filtration and/or vacuum distillation of the water present in the oil, in particular in the event that the pH of the water is less than 4.5.
• the method and apparatus according to the invention provide important advantages as compared with the prior art.
• the invention it is possible to purify a lubricating oil mixture circulated in a pro- cess of chemical forest industry, and thus to reduce the risk of corrosion in the apparatus.
• the invention provides an industrially applicable easy, fast and useful way of deacidification. In addition, investment costs for the apparatus according to the invention are low.
• Fig. 1 illustrates one apparatus according to the invention.
• Example 1 The apparatus according to Fig. 1 is designated to remove or reduce sulfuric acid and/or hydrochloric acid from a lubricating oil mixture in the manufacture of paper and paperboard.
• the apparatus includes a neutralization reactor (3) into which a lubricating oil mixture (10) that contains acid and water is conducted, preferably at slow flow, from a lubricating oil tank (1), such as a circulation lubricating oil or hydraulic oil tank, by delivery means, e.g. delivery piping and/or a pump.
• a lubricating oil tank (1) such as a circulation lubricating oil or hydraulic oil tank
• delivery means e.g. delivery piping and/or a pump.
• the size of the lubricating oil tank may range from 1 to 40 m 3 , e.g. in a circulation lubricating or hydraulic system in the manufacture of paper.
• first heat exchanger (2a) for cooling the lubricating oil mixture from a temperature of approximately 40 to 60 °C to a temperature of approximately 20 °C, under which circumstances the reaction functions in an optimal fashion.
• second heat exchanger (2b) for heating the lubricating oil mixture back to a temperature of approx- imately 40 to 60 ° C, so that the viscosity of the oil mixture would be suitable for a mechanical filter and/or vacuum distillator.
• mechanical filter (5) from 1 to 6 ⁇ abs . , for removing or reducing any desired components from the purified lubricating oil mixture.
• the neutralization reactor (3) includes a bed (6) which contains calcium carbonate and through which the lubricating oil mixture is conducted from below upwards, so that acid, such as sulfuric acid or hydrochloric acid, in the lubricating oil mixture is contacted with calcium carbonate, so that the acid will react with calcium carbonate, forming solid calcium compounds, car- bon dioxide and water.
• the reaction time of the lubricating oil mixture with calcium carbonate is approximately 6min.
• Calcium carbonate is predominantly present in the form of granules of a granule size from 1 to 6 mm.
• the resulting calcium compound such as cal- cium sulfate, i.e. gypsum, can be removed by means of the mechanical filter (5) . This way, the calcium compound does not return to the lubricating oil circulation .
• the apparatus includes a pressure measurement device having at least two pressure measurement sensors (7,8) for determining the pressure difference of the calcium carbonate layer in the neutralization reactor.
• the pressure measurement devices are located just before the neutralization reactor and right after the neutralization reactor.
• the apparatus includes, in connection with the neutralization reactor, an adjustment system (9) for following the carbon dioxide content and adjusting it to a level of less than 20mg/l in the neutraliza- tion reactor.
• the adjustment system includes sensors for following the carbon dioxide level and control means for adjusting the conditions, e.g. lowering the carbon dioxide level, in the neutralization reactor to a suitable level. Instrument air to which the excess carbon dioxide is bound is blown into a pipe adjacent to the lubricating oil mixture inlet pipe at the bottom part of the neutralization reactor, and the air is discharged through the top part of the reactor. The air blowing starts when the adjustment system gives an alarm based on the measurement of the carbon dioxide sensor.
• the alkalinity of water in the lubricating oil mixture is preferably less than 0.8mmol/l.
• the apparatus may optionally include a vacuum distillator (4) in addition to the mechanical filter (5) in the event that the lubricating oil mixture contains a chloride compound, such as calcium chloride, after the neutralization reactor.
• the lubricating oil mixture provided from the neutralization reactor can be conducted through the vacuum distillator for crystallizing the calcium chloride from the lubricating oil mixture. If the lubricating oil mixture contains only sulfuric acid, then the mechanical filter (5) suffices without the vacuum distillator (4) .
• the purified lubricating oil mixture (11) is conducted, e.g. by means of piping and/or a pump, into the lubricating oil tank (1) or a part thereof which holds the purified lubricating oil mixture.
• the reactant of the neutralization reactor (3) is granular calcium carbonate (Ca- C0 3 ) .
• H 2 S0 4 Sulfuric acid present in the lubricat- ing oil mixture and produced in sodium dithionite bleaching reacts with CaC0 3 as follows: H 2 S0 4 + CaC0 3 ⁇ CaS0 4 + C0 2 + H 2 0
• Calcium sulfate (gypsum) (CaS0 4 ) produced in the reaction is filtered by a mechanical filter.
• the water includes sodium chloride (NaCl)
• sulfur dioxide (S0 2 ) produced in the sodium dithionite bleaching as follows :
• the reaction produces sodium sulfate (Glauber's salt) (NaS0 4 ) and hydrochloric acid (HC1) .
• hydrochloric acid reacts with calcium carbonate (CaC0 3 ) as follows:
• Calcium chloride can also be referred to as road salt. It is an agent that causes pitting corrosion. Calcium chloride is crystallized by a vacuum distillator and the crystallized salt is filtered by a mechanical filter. The mechanical filter can also be used to remove sodium sulfate produced in the formation of hydrochloric acid .
• Example 3
• undesirable components such as acid
• the neutralization reactor according to Fig. 1 for purifying the lubricating oil.
• the lubricating oil mixture (10) to be purified contained sulfuric acid dissolved in water in the lubricating oil. Reactions were carried out as described in Example 2. Parallel tests were performed.
• the lubricating oil mixture (10) was conducted into the neutralization reactor (3) .
• the neutralization reactor included a bed (6) which was formed by calcium carbonate granules and through which the lubricating oil mixture was conducted. The amount of the calcium carbonate granules was approximately 1kg.
• the lubricating oil mixture was formed for the test by mixing into 1 liter of paper machine lubricating oil 0.5dl of distilled water of a pH adjusted to a value of approximately 2.5 by sulfuric acid.
• the temperature of the lubricating oil mixture conducted into the neutralization reactor was approximately 20°C.
• the reaction time of the lubricating oil mixture in the neutralization reactor was approximately 6min or approximately lOmin.
• Sulfuric acid dissolved in water in the lubricating oil mixture reacted with calcium carbonate granules, forming the compounds as in Example 2.
• the lubricating oil mixture was recovered in a graduated cylinder, and the water was al- lowed to settle on the bottom of the graduated cylinder.
• the pH of the water was measured.
• the pH of the water after the reaction was approximately 7.

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Citations (4)

• 2012
  • 2012-01-05 FI FI20125015A patent/FI125892B/fi active IP Right Grant
• 2013
  • 2013-01-07 WO PCT/FI2013/050010 patent/WO2013102704A1/en active Application Filing

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