Non-corrosive treatment to enhance pressurized and non-pressurized pulverized coal combustion

Abstract

Methods and compositions for inhibiting corrosion of metal surfaces in a furnace system are disclosed. In one aspect of the invention, pulverized coal is burned as fuel in the presence of a copper ion catalyst/combustion aid. Corrosion is inhibited in these systems by the use of a blend of primary aminoalcohol such as 2-aminoethanol, tertiary aminoalcohol such as triethanol amine, and boric acid or water soluble salt form of the acid.

Description

FIELD OF THE INVENTION

[0001] The invention pertains to methods and compositions for inhibiting corrosion of metal surfaces in contact with a furnace.

BACKGROUND OF THE INVENTION

[0002] The use of copper and other metals to enhance furnace operation is well known. For example, in accordance with the teachings of U.S. Pat. No. 6,077,325 (Morgan et al.), metallic compounds including Zr, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Sn, and Pb may be added to pulverized coal that is burned as fuel in a blast furnace or the like. Pulverized coal is often used as a substitute for a portion of the coke in the preparation of iron involving the reduction of iron oxide with carbon in the blast furnace. This substitution purportedly results in less pollution since coke is being replaced in part, and since coal is less expensive than coke, economies in the process can be realized.

[0003] In typical blast furnace processes, iron bearing materials including iron ore, sinter, scrap, or other iron source along with a fuel, generally coke, and a flux, limestone, or dolomite are charged into the blast furnace from the top. The blast furnace burns part of the fuel to produce heat for melting the iron ore and the balance of the fuel is utilized for reducing the iron and its combination with carbon. The charge in a typical furnace, per ton of pig iron produced, is about 1.7 tons of ore or other iron bearing materials, 0.5-0.65 tons of coke or other fuel, and about 0.25 tons of limestone and/or dolomite. Additionally, from 1.8-2.0 tons of air are blown into the furnace during the process.

[0004] In practice, iron bearing raw materials (sinter, iron ore, pellets, etc.), fuel (coke), and flux (limestone, dolomite, etc.) are charged to the top of the furnace. Heated air (blast) is blown into a blast furnace through openings, known as tuyeres, at the bottom of the furnace. Tuyere stocks are fitted with injection lances through which supplemental fuels (gas, oil, and pulverized coal) are injected. The blast air burns the fuel and facilitates the smelting chemistry that produces iron. Combustion gases from the blast furnace are scrubbed to remove particulate and other noxious gases before being burned in stoves which are used to preheat blast air or in other applications, e.g., coke ovens, boilers, etc.

[0005] As referred to above, when pulverized coal is substituted for a portion of the coke, metals such as those disclosed in the '325 patent may be used as combustion catalysts or aids. These are of benefit since they provide the ability to use lower rank coals in the furnace and allow for greater coke replacement by the pulverized coal. Additionally, they help to minimize “coal cloud” and reduce LOI. Lowered slag content, reduced particulate emissions, and higher quality iron are also potential benefits that may be attributed to the use of these catalysts or aids.

[0006] Copper-based catalysts or combustion aids have become especially popular. However, attendant problems of corrosion have appeared as a result. The problem arises from the corrosion that the product generates on mild steel surfaces that are present in the furnace system in which the combustion catalyst/aid is applied. (As used herein, “furnace” and “furnace systems” refer to ovens, boilers, blast furnaces, or any enclosure in which a fuel is combusted.)

[0007] As a consequence of this corrosion of metallic parts and components of a furnace system, the furnace equipment itself can fail, leading to process down time and costly replacement.

SUMMARY OF THE INVENTION

[0008] We have developed a technology that inhibits corrosion in furnace systems and allows use of metallic based combustion catalysts/aids, especially those employing Cu as the active component. In one aspect of the invention, the corrosion inhibiting treatment of the invention is blended with a copper combustion catalyst/aid to form a protective film on the mild steel surface in contact with the furnace combustion products.

[0009] The corrosion inhibiting treatment comprises a blend of a primary aminoalcohol (i.e., having primary amino function) and boric acid or water soluble salt or the acid. A tertiary aminoalcohol (i.e., having a tertiary amine function) may also be present in the blend. The blend is preferably sprayed onto the pulverized coal in aqueous solution form prior to injection of the coal into the furnace. Alternatively, the treatment may be applied in spray form anywhere in the furnace system including the so-called “fireside” or “cold” ends of the furnace. (See U.S. Pat. Nos. 4,458,006 and 4,224,180 herein incorporated by reference.)

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0010] Metal surfaces, such as mild steel surfaces, of a furnace system are effectively treated in accordance with the invention by a corrosion inhibiting treatment comprising a blend of a primary aminoalcohol and boric acid or water soluble salt form thereof. Additionally, the corrosion inhibiting treatment may comprise a tertiary aminoalcohol. Preferably, the primary aminoalcohol is 2-aminoethanol and the tertiary aminoalcohol is triethanolamine. The invention has proven to be successful, especially in furnace systems in which pulverized coal is burned as fuel in the presence of a copper catalyst/combustion aid.

[0011] The corrosion inhibiting treatment is most preferably provided in the form of an aqueous solution. By the phrase “aqueous solution” as used herein, we mean to encompass not only true chemical solutions, but also dispersions, mixtures, and suspensions. The solution may be sprayed directly over the pulverized coal in an amount of about 100 ml to 1 L of aqueous solution per ton of coal. More preferably, the dosage rate is from about 300 ml-1L of aqueous solution per ton pulverized coal.

[0012] Preferably, the corrosion inhibiting treatment comprises both the 2-aminoethanol and triethanolamine component. In addition, conventional corrosion inhibitors, such as water-soluble gluconic acid salts, preferably sodium gluconate, may be incorporated into the corrosion inhibiting treatment. When the pulverized coal is to be burned in the presence of copper as a catalyst/combustion aid, a copper ion source may also be incorporated into the aqueous solution that is to be sprayed over the coal.

[0013] The invention is also directed to corrosion inhibiting treatment compositions that are adapted for application or spraying onto the fuel in the form of an aqueous solution. In these compositions, the 2-aminoethanol, triethanolamine, and boric acid or salt thereof components may be present in the aqueous solution in the amount of about 1-10 wt %. Sodium gluconate may also be present in the aqueous solution in an amount of about 1-15 wt %. In those instances in which a copper ion source is also present in the aqueous solution, the copper ion source may be present in such an amount as to provide Cu++ in an amount of 1-20 wt %.

[0014] The synergistic blend of 2-aminoethanol, triethanolamine, and borate is not water soluble in the presence of copper. However, when this blend is mixed with the known mild steel corrosion inhibitor, sodium gluconate, the gluconate/“blend” mixture has a high solubility in water even in the presence of copper.

[0015] Exemplary compositions in accordance with the invention include:

aminoalcohol component(s) and boric acid or salt 1-10 wt %
sodium gluconate                 1-15 wt %
copper (as Cu++)*                0-20 wt %
water                            remainder
More preferably, the compositions include 1-10 wt %
aminoalcohol blend of 2-aminoethanol and
triethanolamine with boric acid or salt
sodium gluconate                 1-15 wt %
copper (as Cu++)*                1-20 wt %
*Copper compound adapted to provide requisite amount of Cu++ ion in aqueous solution.

[0016] Based upon preliminary results, it is preferred to provide the copper ion source, sodium gluconate, 2-aminoethanol, triethanolamine, and boric acid or water soluble salt in a single aqueous solution for spray application over the pulverized coal. Exemplary copper ion sources are copper sulfate pentahydrate and copper II-D-gluconate.

[0017] The product which is presently preferred for commercial use comprises about 3% actives of a blend of 2-aminoethanol, triethanolamine, and boric acid, along with 4% active sodium gluconate, and 19% actives of copper sulfate pentahydrate along with sufficient water to equal 100% of the total weight of the formulation.

EXAMPLES

[0018] The invention will be further described in conjunction with the following examples which should be viewed as being illustrative of the invention and should not be construed to limit the invention.

Example 1

Bottle Test Method for Corrosion Rate Comparison

Experimental Procedure

[0019] All corrosion tests were carried out using a bottle test method with mild steel coupons. The coupons were cleaned with tri-sodium phosphate and pumice before and after exposure to the produce solution. Isopropyl alcohol was used to rinse the coupons after cleaning. Each low carbon steel coupon was immersed in a 1% (by weight) copper solution prepared form the indicated stock solution for 24 hours. (Only exceptions are the last two entries in the data table below which involved immersion of the mild steel coupons into the undiluted stock solution.) Total test solution weight was 100 grams. Each test was conducted at 30° C. in a water bath shaking at 40 rpm. Corrosion rates were determined by the amount of weight loss that occurred in 24 hours. All formulations tested were run in duplicate, so the corrosion rates shown represent the average of the two. The level of copper (as Cu2+ in EP9587 (4.84%) was maintained for each new stock formulation prepared. The percentage of surfactant and water and the source of copper ion were the variables manipulated. All blends were prepared based on the weight % of each component. In addition, an 11-day test using undiluted stock solutions was carried out with the better of the two corrosion blends.

Experimental Results

[0020] Copper Based Combustion Enhancer (CBCE)=19% copper sulfate pentahydrate (which is 4.84% Cu2+, the level found in every stock solution tested below)/1.6% alkylpolyglucoside surfactant (Triton BG-10).

[0021] Corrosion Inhibitor Blend (CIB)=2-aminoethanol, triethanolamine, and boric acid (Maxhib AB-400)—available from Chemax, Rutgers Organics Corporation, Greenville, S.C. 29606.

[0022] Data Table 1 below shows the above listed as CBCE and CIB with the appropriate concentrations used.

TABLE 1
		Corrosion Rate	% Reduction of
	Composition of Stock Solution	(mpy) on Low	Corrosion Rate
Example	Tested (by % weight)	Carbon Steel	(relative to CBCE)
Control	CBCE (4.84% Cu) [CONTROL]	935	NA
C-1	Similar to CBCE but with the	25	97
	4.84% Cu coming from Copper(II)-
	D-Gluconate instead of
	CuSO4.5H2O
C-2	CBCE with an added 1% Sodium	959	0
	Gluconate
C-3	CBCE with an added 6.7% Sodium	974	0
	Gluconate
C-4	CBCE with an added 9% Sodium	1000	0
	Gluconate
C-5	Similar to the CBCE but with 1% of	968	0
	the Cu coming form Copper(II)-D-
	Gluconate & the other 3.84% Cu
	coming from CuSO4.5H2O
C-6	CBCE but with the pH raised 1 unit	964	0
	with NH4OH
C-7	Similar to the CBCE but with 1% of	955	0
	the Cu coming from Copper(II)-D-
	Gluconate & the other 3.84% Cu
	coming from CuSO4.5H2O. In
	addition 0.1% Zinc was added.
C-8	Similar to the CBCE but with 1% of	466	50
	the Cu coming from Copper (II)-D-
	Gluconate & the other 3.84% Cu
	coming from CuSO4.5H2O. In
	addition, pH was raised one-half
	unit with NH4OH.
C-9	Similar to the CBCE but with 1% of	175	81
	the Cu coming from Copper(II)-D-		(Product was not
	Gluconate & the other 3.84% Cu		stable.)
	coming from CuSO4.5H2O. In
	addition, pH was raised one unit
	with KOH.
C-10	Similar to the CBCE but with 1% of	212	77
	the Cu coming from Copper(II)-D-		(Product was not
	Gluconate & the other 3.84% Cu		stable.)
	coming from CuSO4.5H2O. In
	addition, pH was raised one unit
	with NaOH.
C-11	Similar to the CBCE but with 1% of	174	81
	the Cu coming from Copper(II)-D-		(Product was not
	Gluconate & the other 3.34% Cu		stable.)
	coming from CuSO4.5H2O. In
	addition, pH was raised one unit
	with NaOH.
C-12	Similar to the CBCE but with 1% of	147	84
	the Cu coming from Copper(II)-D-		(Product was not
	Gluconate & the other 3.84% Cu		stable.)
	coming from CuSO4.5H2O. In
	addition, pH was raised one unit
	with NH4OH.
C-13	Similar to the CBCE but with	900	4
	1.35% alkylpolyglucoside surfactant
	(Triton BG-10) instead of 1.6%,
	and 0.25% alkoxylated mercaptan
	(Burco TME added as well.
C-14	Similar to the CBCE but with	957	0
	1.35% alkylpolyglucoside surfactant
	(Triton BG-10) instead of 1.6%,
	and 1.5% alkoxylated mercaptan
	(Burco TME added as well.
C-15	Similar to the CBCE but with 1.6%	838	10
	alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6%
	alkoxylated amine.
C-16	Similar to the CBCE but with 1.6%	787	16
	alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6%
	alkoxylated amine.
C-17	Similar to the CBCE but with 1.6%	808	14
	alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6%
	proprietary surfactant blend with
	propargyl alcohol (Maxhib PA 315).
C-18	Similar to the CBCE but with 1.6%	852	9
	alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6% of
	a quaternary aryl ammonium
	chloride (Dodicor 2565).
C-19	Similar to the CBCE but the 1.6%	998	0
	alkylpolyglucoside surfactant
	(Triton BG-10) was not added.
	Instead, 1% boric acid & 1% EDTA
	were added.
C-20	Similar to the CBCE but the 1.6%	913	2
	alkylpolyglucoside surfactant
	(Triton BG-10) was not added.
	Instead 5% proprietary surfactant
	blend with propargyl alcohol
	(Maxhib PA 315) was added.
C-21	Similar to the CBCE but the 1.6%	543	42
	alkylpolyglucoside surfactant
	(Triton BG-10) was not added.
	Instead, 5% quaternary aryl
	ammonium chloride (Dodicor 2565)
	was added.
C-22	Similar to the CBCE but the 1.6%	576	38
	alkylpolyglucoside surfactant
	(Triton BG-10) was not added.
	Instead, 10% quaternary aryl
	ammonium chloride (Dodicor 2565)
	was added.
C-23	Similar to the CBCE but the 1.6%	875	6
	alkylpolyglucoside surfactant
	(Triton BG-10) was replaced by
	1.6% of a quaternary aryl
	ammonium chloride (Dodicor
	2565). In addition, pH was raised
	one unit w/NH4OH.
C-24	Similar to the CBCE but with the	832	11
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6% of
	a quaternary aryl ammonium
	chloride (Dodicor 2565). In
	addition, 1% of the Cu was from
	Copper(II)-D-Gluconate & the other
	3.84% came from CuSO4.5H2O.
	The pH was raised one unit
	w/NH4OH as well.
C-25	Similar to the CBCE but with the	692	26
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6% of
	a proprietary surfactant blend with
	propargyl alcohol (Maxhib PA 315).
	In addition, 1% of the Cu was from
	Copper(II)-D-Gluconate & the other
	3.84% came from CuSO4.5H2O.
	The pH was raised one unit with
	NaOH as well.
Example 1	Similar to the CBCE but with the	222	76
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	2.27% CIB (Maxhib AB 400) &
	6.7% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 2	Similar to the CBCE but with the	213	77
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	2.3% CIB (Maxhib AB 400) &
	5.4% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 3	Similar to the CBCE but with the	223	76
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	2.8% CIB (Maxhib AB 400) &
	4.3% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 4	Similar to the CBCE but with the	230	75
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	3.0% CIB (Maxhib AB 400) &
	4.0% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 5	Similar to the CBCE but with the	181	81
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	3.0% CIB (Maxhib AB 400) &
	5.0% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 6	Similar to the CBCE but with the	541	42
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	3.5% CIB (Maxhib AB 400) &
	4.2% sodium gluconate were added
	to the 4.84% Cu (from 19% copper
	sulfate pentahydrate).
Example 7	Similar to the CBCE but with the	200	79
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	2% CIB (Maxhib AB 400) was
	added. In addition, 1% Cu came
	from Copper(II)-D-Gluconate &
	3.84% Cu came from copper sulfate
	pentahydrate to make up the 4.84%
	total Cu amount.
Example 8	Similar to the CBCE but with the	146	84
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	2.5% CIB (Maxhib AB 400) was
	added. In addition, 1% Cu came
	from Copper(II)-D-Gluconate &
	3.84% Cu came from copper sulfate
	pentahydrate to make up the 4.84%
	total Cu amount.
C-27	Similar to the CBCE but with the	820	12
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) replaced by 1.6%
	modified complex amine (Deterge
	AT-100). In addition, 1% Cu came
	from Copper(II)-D-Gluconate &
	3.84% Cu came from copper sulfate
	pentahydrate to make up the 4.84%
	total Cu amount.
C-28	Similar to the CBCE but with the	775	17
	1.6% alkylpolyglucoside surfactant
	(Triton BG-10) not added. Instead,
	3% modified complex amine
	(Deterge AT-100) was added. In
	addition, 1% Cu came from
	Copper(II)-D-Gluconate & 3.84%
	Cu came from copper sulfate
	pentahydrate. The pH was raised
	one unit with NaOH as well.
11-Day Bottle Test Using Undiluted Stock Solutions
Example 9	Undiluted CBCE tested for 11 days	4961	NA
	(Control for 11-day test)
	Undiluted Blend Tested for 11 Days vs.	781	84
	CBCE. In this case, the CBCE prepared did
	not have the 1.6% alkylpolyglucoside
	surfactant (Triton BG-10). Instead, 3.0%
	CIB(Maxhib AB 400) & 4.0% sodium
	gluconate were added to the 4.84% Cu (from
	19% copper sulfate pentahydrate).

Example 2

[0023] The procedures reported in Example 1 were again performed in conjunction with comparative treatments and treatments in accordance with the invention. Results are shown in Table 2.

		Corrosion Rate	% Reduction of
	Composition of Stock	(mpy) on Low	Corrosion Rate
Example	Solution Tested (by wt %)	Carbon Steel	(relative to EP9587)
Control	EP9587 [CONTROL]	935	NA
C-29	EP9587 W/4.84% Cu from	25	97
	Copper(II)-D-Gluconate instead		(Increase in raw
	of CuSO4.5H2O		material cost higher
			than 20%.)
C-30	EP9587 1% Sodium	959	0
	Gluconate.
C-31	EP9587 6.7% Sodium	974	0
	Gluconate.
C-32	EP9587 9% Sodium	1000	0
	Gluconate.
C-33	EP9587 1% Cu from	968	0
	Copper(II)-D-Gluconate &
	3.84% Cu from CuSO4.5H2O.
C-34	EP9587 & pH raised 1 unit w/	964	0
	NH4OH.
C-35	EP9587 w/ 1% Cu from	955	0
	Copper(II)-D-Gluconate &
	3.84% from CuSO4.5H2O w/
	0.1% zinc.
C-36	EP9587 w/ 1% Cu from	466	50
	Copper(II)-D-Gluconate &
	3.84% from CuSO4.5H2O &
	pH raised one half unit w/
	NH4OH.
C-37	EP9587 w/ 1% Cu from	175	81
	Copper(II)-D-Gluconate &		(Product was not
	3.84% from CuSO4.5H2O &		stable.)
	pH raised one unit w/ KOH.
C-38	EP9587 w/ 1% Cu from	212	77
	Copper(II)-D-Gluconate &		(Product was not
	3.84% from CuSO4.5H2O &		stable.)
	pH raised one unit with
	NAOH.
C-39	EP9587 w/ 1.5% Cu from	174	81
	Copper(II)-D-Gluconate &		(Product was not
	3.34% from CuSO4.5H2O w/		stable.)
	pH raised one unit with NaOH.
C-40	EP9587 w/ 1% Cu from	147	84
	Copper(II)-D-Gluconate &		(Product was not
	3.84% from CuSO4.5H2O &		stable.)
	pH raised one unit w/NH4OH.
C-41	EP9587 w/ 1.35% Triton BG-	900	4
	10 & 0.25% Burko TME.
C-42	EP9587 w/ 0.1% Triton BG-10	957	0
	& 1.5% Burko TME
C-43	EP9587 w/ Triton BG-10	838	10
	replaced by alkoxylated amine.
C-44	EP9587 w/ Triton BG-10	787	16
	replaced by alkoxylated amine.
C-45	EP9587 w/ Triton BG-10	808	14
	replaced by Maxhib PA 315.
C-46	EP9587 w/ Triton BG-10	852	9
	replaced by Dodicor 2565.
C-47	EP9587 w/ Triton BG-10	998	0
	replaced by 1% Boric Acid &
	EDTA.
C-48	EP9587 w/ Triton BG-10	913	2
	replaced by Maxhib PA 315.
C-49	EP9587 w/ Triton BG-10	543	42
	replaced by 5% Dodicor 2565.
C-50	EP9587 w/ Triton BG-10	576	38
	replaced by 10% Dodicor
	2565.
C-51	EP9587 w/ Triton BG-10	875	6
	replaced by Dodicor 2565 &
	pH raised one unit w/ NH4OH.
C-52	Triton BG-10 replaced by	832	11
	Dodicor 2565 & 1% Cu from
	Copper(II)-D-Gluconate &
	3.84% from CuSO4.5H2O and
	pH raised one unit w/ NaOH.
Example 10	Triton BG-10 replaced by	692	26
	Maxhib PA 315 & 1% Cu
	from Copper(II)-D-Gluconate
	& 3.84% from CuSO4.5H2O
	and pH raised one unit w/
	NaOH.
Example 11	Triton BG-10 replaced by	222	76
	2.27% Maxhib AB 400 &
	6.7% sodium gluconate and
	19% copper sulfate
	pentahydrate.
Example 12	Triton BG-10 replaced by	213	77
	2.3% Maxhib AB 400 & 5.4%
	sodium gluconate and 19%
	copper sulfate pentahydrate.
Example 13	Triton BG-10 replaced by	223	76
	2.8% Maxhib AB 400 & 4.3%
	sodium gluconate and 19%
	copper sulfate pentahydrate.
Example 14	Triton BG-10 replaced by	23	75
	3.0% Maxhib AB 400 & 4.0%
	sodium gluconate and 19%
	copper sulfate pentahydrate.
Example 15	Triton BG-10 replaced by	181	81
	3.0% Maxhib AB 400 & 5.0%
	sodium gluconate and 19%
	copper sulfate pentahydrate.
Example 16	Triton BG-10 replaced by	541	42
	3.5% Maxhib AB 400 & 4.2%
	sodium gluconate and 19%
	copper sulfate pentahydrate.
Example 17	Triton BG-10 replaced by 2%	200	79
	Maxhib AB 400 & 1% Cu
	from Copper(II)-D-Gluconate
	& 3.84% from copper sulfate
	pentahydrate.
Example 18	Triton BG-10 replaced by	146	84
	2.5% Maxhib AB 400 & 1%
	Cu from Copper(II)-D-
	Gluconate & 3.84% from
	copper sulfate pentahydrate.
C-53	Triton BG-10 replaced by	820	12
	Deterge AT-100 & 1% Cu
	from Copper(II)-D-Gluconate
	& 3.84% from copper sulfate
	pentahydrate.
C-54	Triton BG-10 replaced by 3%	775	17
	Deterge AT-100 & 1% Cu
	from Copper(II)-D-Gluconate
	& 3.84% from copper sulfate
	pentahydrate & pH raised one
	unit with NaOH.
C-55	Undiluted EP9587 tested for 11	4961	NA
	days (Control for 11-day test).
Example 19	Undiluted Blend Tested for 11	781	84
	days vs. EP9587: Triton BG-
	10 replaced by 3.0% Maxhib
	AB400 & 4.0% sodium
	gluconate and 19% copper
	sulfate pentahydrate.

Claims

1. A method of inhibiting corrosion of metal surfaces in a furnace wherein coal is burned as a fuel, said method comprising burning said coal in the presence of a corrosion inhibiting treatment comprising an aminoalcohol.

2. A method as recited in claim 1 wherein said corrosion inhibiting treatment further comprises boric acid or water soluble salt of said boric acid.

3. A method as recited in claim 2 wherein said coal is pulverized and said treatment is applied in the form of an aqueous solution over said pulverized coal.

4. A method as recited in claim 2 wherein said treatment is sprayed in aqueous solution form into said furnace.

5. A method as recited in claim 2 wherein said aminoalcohol comprises a primary aminoalcohol having a primary amine functionality.

6. A method as recited in claim 5 wherein said aminoalcohol further comprises a tertiary aminoalcohol having tertiary amine functionality.

7. A method as recited in claim 5 wherein said aminoalcohol further comprises 2-aminoethanol.

8. A method as recited in claim 6 wherein said tertiary aminoalcohol is triethanolamine.

9. A method as recited in claim 8 wherein said coal is burned in the presence of copper.

10. A method as recited in claim 3 wherein said aqueous solution is sprayed over said pulverized coal in an amount of about 100 ml-1L of said aqueous solution per ton of said pulverized coal.

11. A method as recited in claim 10 wherein said aqueous solution is sprayed over said pulverized coal in an amount of about 300 ml-1L per ton of said pulverized coal.

12. A method as recited in claim 8 wherein said 2-aminoethanol, triethanolamine, and boric acid or salt thereof are present in combination in aqueous solution in an amount of about 1-10 wt %.

13. A method as recited in claim 12 further including sodium gluconate in said aqueous solution, said sodium gluconate being present in said aqueous solution in an amount of between about 1-10 wt %.

14. In a method in which pulverized coal is burned as a fuel in a furnace in the present of copper to enhance the operation of the furnace, the improvement comprising also burning said coal in the presence of a corrosion inhibiting treatment, said treatment comprising 2-aminoethanol, triethanolamine and boric acid or water soluble thereof.

15. A method as recited in claim 14 wherein said copper and said corrosion inhibiting treatment are both sprayed onto said coal in the form of a single aqueous solution.

16. A method as recited in claim 14 wherein said corrosion inhibiting treatment further comprises gluconic acid or water soluble salt thereof.

17. A method as recited in claim 16 wherein said corrosion inhibiting treatment comprises sodium gluconate.

18. A method as recited in claim 17 wherein said 2-aminoethanol, triethanolamine and boric acid or salt thereof are present in combination in said aqueous solution in an amount of about 1-about 10 wt %, said sodium gluconate being present in said aqueous solution in an amount of about 1-15 wt % and wherein said copper is present in said aqueous solution as Cu++ in an amount of about 1-20 wt %, and wherein about 100 ml-1L of said aqueous solution is sprayed onto said pulverized coal.

19. Corrosion inhibiting composition comprising an aqueous solution comprising: (a) 2-aminoethanol; (b) triethanolamine; and (c) boric acid or water soluble salt form.

20. Corrosion inhibiting composition as recited in claim 19 further comprising (d) sodium gluconate.

21. Corrosion inhibiting composition as recited in claim 20 further comprising (e) a copper ion source.

22. Corrosion inhibiting composition as recited in claim 21 wherein said copper ion source is copper sulfate pentahydrate or copper(II)-D Gluconate.

23. Corrosion inhibiting composition as recited in claim 21 wherein said (a), (b) and (c), in combination, are present in said aqueous solution in an amount of about 1-10 wt %, said (d) is present in said aqueous solution in an amount of about 1-15 wt % and wherein said copper ion source (e) is present in an amount sufficient to provide from about 1-20 wt % of Cu++ ion in said aqueous solution.