WO2001040415A2

WO2001040415A2 - Additive for preventing deposits and corrosion of heating furnaces or steam generators, and method for its obtaining

Info

Publication number: WO2001040415A2
Application number: PCT/RO2000/000023
Authority: WO
Inventors: C. Gheorghe Anghelache; Niculae Viciu; I. Elena Florina Gherman
Original assignee: Icerp-S.A.
Priority date: 1999-12-03
Filing date: 2000-11-23
Publication date: 2001-06-07
Also published as: WO2001040415A3; RO116417B1

Abstract

An additive is described as preventing deposits and corrosion of heating furnaces or steam generators, which is characterized by the fact that it is a water solution, containing 25 40 g/l K+ ions, 60 80 g/l NO¿3?- ions, a maximum amount of 50 mg/l chromium, ethylic alcohol or mono ethylene glycol in a maximum proportion of 35 % wt., 5 11 g/l NH¿4?+ ions, and having a pH value 8 and a congealing temperature in the range of -5 -20 °C. The method for obtaining this additive comprises dissolution of components, filtration of solutions, homogenization and additivation of the mixture, followed by adjusting its pH to a value equal or greater than 8. The present additive is useful for preventing corrosion phenomena and deposits resulted in furnaces and steam generators, which use any gaseous, liquid or solid fuels.

Description

ADDITIVE FOR PREVENTING DEPOSITS AND CORROSION OF HEATING FURNACES OR STEAM GENERATORS, AND METHOD FOR ITS OBTAINING

The present invention describes an additive for preventing deposits and corrosion of heating furnaces or steam generators, and a method for its obtaining, this additive being useful for the ;reatment of the combustion gases by injection in the combustion chamber or in the fuel just before its entrance to the burner

For heating generation in technological, domestic or energetic purposes, the gaseous liquid or solid fuels are burned resulting in various compounds responsible of the low and high temperature corrosions, of the formation of deposits and environmental pollution

One of the commonly used methods tor preventing corrosion, deposit formation and environmental pollution phenomena is the use of additives There are a large vaπety of liquid and solid additives [1-5] in industrial practice

Prior art patents relateo to the present invention include the following

RO Pat No 114507B describes a composition for the combustion a.r treatment at furnace equipments, containing sodium nitrate, potassium nitrate, ammonium nitrate and / or ceπum nitrate, in concentration of 0,25 150g/l, with or without magnesium nitrate, in concentration of 100 800g/l and / or potassium dichromate, in concentration of 0,4 104g/l, in function of the flow and the characteristics of the fuel, as well as in function of the flow and the temperature of the treated air fraction

RO Pat No 1 14507B mentions the improving of the combustion air with the suspensions of burning improver and deposit control, using 0.025-0, 25ppm Cr⁶\ 0, 15-1 ,5ppm NO^3" and 0,75-7, 5ppm Ce^4* in the fuel oil

The e additives have the following disadvantages

- they influence negatively on the burners by alteration of the atomizer passage of fuels

- they are obtained through laborious processes and with equipments of high energy consumption (colloidal mills, centrifugal settlers, methods of obtaining in situ colloidal dispersions),

- they need complex equipments of dosage at stack gases or fuels treatment (blenders, dispensing devices),

The technical problem solved by the invention is the increasing additive stability at transport and storage, at low temperatures (till -21 °C)

The additive in conformity with this patent eliminates the disadvantages, by solving the technical problem mentioned above and being made of watery solution and containing 25-40 g/l K" ions, derived from KN03, 60-80 g/l N0₃ ions derived from KN0₃ and NH₄N0₃, 5-11 g/l NH₄ ^* ions, derived from (NH4)₂Cr₂0₇ NH₄OH and NH4NO₃ 30-50 mg/l Cr^6*, derived from (NH4)₂Cr₂0₇, 5-35 wt ethylic alcohol or mono ethylene glycol, and having a pH value ^" 8 and a congealing temperature in the range of -5 - -20° C

The method for obtaining the additive, in conformity with the patent, eliminates the disadvantages mentioned and ; characterized by preparing a solution of potassium nitrate, by blending 4-10 parts KN03 with 30-100 parts demmeralized water, and a solution of NH4N03, by blending 1 -4 parts ammonium nitrate with 5-25 parts demmeralized water, by filtering these two solutions and by mixing in a proportion of 5-30 parts of filtered solution of ammonium nitrate to 35-110 parts of filtered solution of potassium nitrate, by adding to this mixture 0,6-1 5 parts solution of 1% wt ammonium dichromate in water, by homogenizing using mechanical stimng , by add.ng 5-35 parts ethylic alcohol or mono ethylene glycol, by adding a 25% ammonia solution to adjust pH to a value equal or greater than 8 , the parts being expressed in wt

The use of this invention presents the following advantages

- it provides the stability of the product on a large temperature range (+50 - -21 °C)

- it reduces the complexity of additive synthesis process through simple dissolving operations, through filtration and homogenizatio i,

- it reduces the energetic consumption in the process of additive fabπcation,

- it facilitates combustion processes due to the Cr⁶⁺ ions derived from (NH₄)₂Cr₂0₇, in the concentration already mer tioned, ions which provide advanced lonization of the gases,

- it eliminates the disadvantage of alteration of the burners, extending their life time through direct injection of additive in the combustion room,

- it reduces the quantity of deposits on the heat exchanger surfaces, facilitating their cleaning operations,

- it reduces the air pollution by reducing considerably the content of NO_x, S0₂ and SO3 in the stack gases, due to the decreasing temperature in the combustion room and to presence of K+ ion in the concentration already mentioned,

- it increases the furnace efficiency as a result of the increasing degree of heat recovery from the stack gases,

- it increases the durability of equipments as a result of corrosion phenomena preventing on the stack gases flow

As follows, there are presented four examples for obtaining the additive, in conformity with the invention Example 1.

4 1 parts wt of potassium nitrate and 48 parts wt demmeralized water are introduced into an 800-cm³ cylindrical glass vessel, at room temperature and the mixture is homogenized using a magnetic strrer up to the total dissolution of the nitrate In a similar vessel, 5 parts wt of demir_.eralized water and 1 7 parts wt of ammonium nitrate are homogenized Ubing a magnetic stirrer until the ammonium nitrate is completely dissolved These two solutions obtained as described previously are filtered separately and mixed in a proportion of 52 parts of potassium nitrate solution to 7 parts wt of ammonium nitrate solution, followed by mechanical homogemzation for 30 minutes To the new obtained solution is added mono ethylene glycol or ethylic alcohol and an 1 % wt ammonium dichromate solution in water in a proportion of 0,6 parts wt relative to the mixture of the two solutions The resulting mixture is adjusted for a pH I ' 8, using a 25% wt solution of ammonia in distilled water

By this procedure, it is obtained an additive for preventing deposits and corrosion of heating furnaces or steam generators characteπzed by the fact that it is a water solution containing 26 8 g/l K⁺ ions, 63 7 g/l N0₃ ions 6 g/l NH₄ ⁺ ions, 30 mg/l chromium, 5% mono ethylene glycol or ethylic alcohol , having a pH value i ι 8 and a congealing temperature of -6°C.

Example 2.

Into a cylindrical vessel like the one deεcπned in Example 1 , 9 parts of potassium nitrate and 100 parts of demmeralized water are added and stirred with a magnetic stirrer up to the total dissolution of the nitrate Into another similar vessel, 4 parts of ammonium nitrate and 12 parts of demmeralized water are added, followed by stirnng until the nitrate is completely dissolved These two solutions are filtered and mixed in a proportion of 110 parts potassium nitrate solution to 16 parts of ammonium nitrate and to this mixture is added 10% wt mono ethylene glycol or ethylic alcohol and a 1 % wt solution of ammonium dichromate is added in a proportion of 1part wt , followed by homogemzation for 15 minutes The new product obtained is corrected for a pH value equal or greater than 8, using an ammonia solution of 25 % wt in distilled water

Thus, it is obtained an additive for preventing deposits and corrosion of heating furnaces or steam generators, characterized by the fact that it is a watei solution having a pH value ϋ 8, containing 35 1 g/l K^* ions, 65 g/l N0₃ ions, 6 g/l NH₄ ⁺ ions, 40 mg/l chromium, 10% mono ethylene glycol or ethylic alcohol and having a congealing temperature of -6°C

Exan pie 3.

Into a cylindπcal vessel like the one described in Example 1 7 parts of potassium nitrate and 30 parts of demmeralized water are added and stirred, at room temperature up to the total dissolution of the nitrate Into another similar vessel 3 parts of ammonium nitrate and 25 parts of demmeralized water are added followed by stirring until the salt is completely dissolved These two solutions are filtered and mixed in a proportion or 37 parts potassium nitrate solution to 28 parts of ammonium nitrate The newly obtained solution is mixed with ethylic alcohol in a proportion of 65% wt to 35 %wt , respectively, and then to this mixture a 1% wt. solution of ammonium dichi ornate is added in a proportion of 1 5 parts wt The mιxtu^re obtained is corrected for a pH value equal or greater than 8, using an ammonia solution of 25 % wt in distilled water

Thus, it is obtained an additive for preventing deposits and corrosion of heating furnaces or steam generators, containing a watery solution of 29 g/l K⁺ ions, 65 g/l N0₃ ^" ions, 6 5 g/l NH ions, 50 mg/l chromium, 35% wt mono ethylene glycol or ethylic alcohol and having a pH value 1 1 8 and a congealing temperature of -21 °C

Example 4.

Into a cylindrical vessel like that described in Example 1 , 9 parts of potassium nitrate and 40 parts of demmeralized water are added and stirred with a mechanical device up to the total dissolution of the nitrate Into another similar vessel, 4 parts of ammonium nitrate and 18 parts of demmeralized water are added, followed by stirring until the salt is completely dissolved. The solutions thus obtained are filtered separately and mixed in a proportion of 49 parts potassium nitrate solution to 22 parts of ammonium nitrate The solution obtained is then mixed with mono ethy.ene glycol for a final proportion of 29% wt mono ethylene glycol To this mixture, a 1% wt. solution of ammonium dichromate is added in a proportion of 1 5 parts wt , and then the pH is corrected for a value equal or greater than 8, using an ammonia solution of 25 % wt in distilled water

Thus, it is obtained an additive for preventing deposits and corrosion of heating furnaces or steam generators, characterized by the fact that it is a water solution, containing 36 g/l K^* ions, 77 g/l N0₃ ^" ions, 10 g/l NH₄ ⁺ ions, 50 mg/l chromium, 29% mono ethylene glycol and having a pH value i i 8 and a congealing temperature of -21 °C

APPLICATIONS

It is introduced in an autoclave a quantity of 413 kg demmeralized water which is heated under permanent stirring at a temperature of 50-60°C after which it is added 72,5 potassium nitrate The autoclave content is maintained under stirring for 1 h at a temperature of 50-60°C

It is introduced in another autoclave 100 kg demmeralized water, which is heated at 30-40 "C and then it is introduced 30kg ammonium nitrate

The blending is maintained at 30-40 °C for 1 h, under permanent stimng, then the solution obtained is filtrated A clear ammonium nitrate solution is obtained, which is blended with the potassium nitrate solution The blending of the two solutions is homogenized for 30 mm at 30-40 °C The solution obtained is alkalized by tieatment with ammonium watery solution For this purpose in the autoclave with nitrates solution it is introduced 6 7 kg ammonia solution of 25% wt Then in the autoclave it is added 428 Kg mono ethylene glycol and the blending is maintained under permanent stirring, for 30 nin, at 30-40°C

To control in time the pH value, to the product it is added 6 8 Kg alcoholic solution of phenolphthalein Then, to the solution from the autoclave it is added 10 Kg solution of ammonium dichromate 1 % in water The product is kept under stirring for 30 mm at 20-35°C

Thus, it is obtained a clear red product, with pH π 8 5, d ₄ ²⁰ =1 056 and congealing temperature = -21°C, which is used at stack gases treatment in the heating furnaces and steam generators

In the refinery furnace, which burns liquid fuel with 0 62% wt sulfur it results a concentration of S0₂+S0₃ of 365-400 mg/Nm³ and a corrosion rate of stack gases flow 0 1 mm per year

By tι eating stack gases with the product obtained as described above in doses of 1l/8h, injected during 2-3 mm in the combustion room, it is obtained a reduction of S0₂ and S0₃ concentration in the stack gasts to 240-280 mg / Nm³, and the corrosion rate to 0 03-0 035 mm per year Applying the treatment, deposits from the air pre-heater are eliminated by reducing the stack gases temperature at chin ley from 270°C to 210°C and resulting a temperature increase of the preheated air from 180 °C to 250 "C

Stack gases treatment at a steam boiler which consumes liquid fuel with a sulfur content of 0 7% wt by continuously injecting the obtained product in the combustion room at a treatment rate of 0 6 %o wt relative to the burned fuel reduces the S0₂ and S0₃ content in stack gases from 420 mg/Nm³ to 200 mg/Nm³ extending the working time of the boiler between two cleanings with 100^vo and reducing the fuel consumption with 8% wt The corrosion rate on the stack gases flow was reduced from 0 12 mm per year to 0 035 mm per year

Claims

What is claimed is

1 An additive for preventing deposits and corrosion of heating furnaces or steam generators, characterized by th fact that it is a watery solution, containing 25-40 g/l K⁺ ions, derived from KN0₃, 60-80 g/l N0₃ ^' ions derived from KN0₃ and NH₄N0₃, 5-11 g/l NH₄ ⁺ ions, derived from (NH₄)₂Cr₂0₇, NH₄OH and NH₄N0₃, 30-50 mg/l Cr₆₊, derived from (NH₄)₂Cr₂0₇, 5-35% wt ethylic alcohol or mono ethylene glycol and having a pH value ' ' 8 and a congealing temperature in the range of -5 - -20° C

2 The method for obtaining the additive of claim 1 is characteπzed by preparing a solution of potassium nitrate, by blending 4-10 parts KN0₃ with 30-100 parts demmeralized water, and a solution of NH₄N0₃, by blending 1 -4 parts ammonium nitrate with 5-25 parts demmeralized water, by filtering these two solutions and by mixing in a proportion of 5-30 parts of filtered solution of ammonium nitrate to 35-110 parts of filtered solution of potassium nitrate, by adding to this mixture 0,6-1 5 parts solution of 1% wt ammonium dichromate in water, by homogenizing using mechanical stimng , by adding 5-35 parts ethylic alcohol or mono ethylene glycol, by adding a 25% ammonia solution to adjust pH to a value equal or greater than 8 , the parts being expressed