Corrosion inhibitor for use in blast furnace gas pipe system

Abstract

Compositions and methods are provided for reducing, inhibiting, or preventing corrosion of a surface in a piece of equipment, using a corrosion inhibitor composition comprising a triazole and a solvent. Preferably, the corrosion inhibitor composition reduces corrosion rate of equipment in contact with a blast furnace gas condensate that can be present in a blast furnace gas pipe.

Description

CORROSION INHIBITOR FOR USE IN BLAST FURNACE GAS PIPE SYSTEMFIELD OF THE INVENTION

[0001] Compositions and methods are provided for reducing, inhibiting, or preventing corrosion of a surface in a piece of equipment, using a corrosion inhibitor composition comprising a triazole and a solvent. Preferably, the corrosion inhibitor composition reduces corrosion rate of equipment in contact with a blast furnace gas condensate that can be present in a blast furnace gas pipe.BACKGROUND OF THE INVENTION

[0002] Steelmaking processes typically have three processes. Primary steelmaking involves smelting iron into steel. Secondary steelmaking involves adding or removing elements such as allying agents and / or dissolved gases. Tertiary steelmaking involves casting the steel into sheets, rolls, or other forms. Each of these processes can consist of many different techniques.

[0003] Typically, electric arc furnace steelmaking is used in the United States. This process manufactures steel from scrap metal or direct reduced iron melted by electric arcs. A batch of iron is loaded into the electric arc furnace, sometimes with molten steel from a previous batch, and heated. Fluxes (e.g., limestone) are added to protect the lining of the vessel and improve removal of impurities. The typical electric arc furnace capacity is about 100 tons and produces steel every 40 to 50 minutes.

[0004] Blast furnace steelmaking requires melting iron ore at a very high temperature (1700 °C or >3000 °F) in the presence of oxygen and coke (a type of coal). Coke, ores, and flux are continuously supplied through the top of the furnace and a hot blast of air, sometimes with oxygen enrichment, is blown into the lower section of the furnace so that chemical reactions take place throughout the furnace as the starting materials fall down. The products are molten metal and slag at the bottom of the furnace and blast furnace gases exit from the top of the furnace. At the high temperatures in the blast furnace, the iron ore reacts with oxygen and coke to form carbon dioxide. A small number of carbon atoms bond with the iron to form pig iron, which is an intermediate in the steelmaking process since its carbon content is too high (e.g., about 4%).

[0005] Blast furnaces and other systems used to smelt industrial metal release high pressure and high temperature gases that can be utilized as a heat or electric source. The gas that emerges from the top of the blast furnace is typically cleaned to remove large particulate matter, and used in a metal-producing plant as a fuel for heating or is fed into a top-pressure recovery turbine to generate electricity. Toppressure recovery turbines (TRTs) are rotary mechanical devices used to extract energy from blast furnace gas by converting gas pressure and thermal energy to mechanical energy. Top-pressure recovery turbines generate power utilizing the expansion of gas volume with the reduction of its pressure. The high-temperature high-pressure gas enters the top-pressure recovery turbine where it expands down to the exhaust pressure, producing a shaft work output. The turbine shaft work can be used to power a device such as an electric generator coupled to the shaft. Generally, top-pressure recovery turbines increase the efficiency of blast furnace processes.

[0006] The composition of blast furnace gas can vary based on the particular design of the blast furnace, its size, and the type of smelting. Blast furnace gas typically comprises ammonia, hydrochloric acid, sulfuric acid, nitrogen, carbon dioxide, carbon monoxide, sulfur dioxide, hydrogen, hydrogen sulfide, hydrogen cyanide, and water vapor at high temperature (e.g., greater than 70 °C) and elevated pressure (e.g., greater than 1 bar). Under certain conditions, acidic and basic blast furnace gases combine and precipitate to form deposits on turbine surfaces. For example, ammonia and hydrochloric acid combine to form ammonium chloride, a salt that readily adheres to turbine surfaces including the surfaces of blades and the inner cylinder.

[0007] Deposition of particulate matter on turbine surfaces can result in performance loss and equipment damage. For example, salt deposition on turbine blades can lead to blade work resistance, which results in a reduction in energy generated by the turbine. In addition, deposited salts can ionize into their respective acid and base, forming strong acid or base condensates on turbine surfaces. Strong acids and bases are corrosive substances that can destroy or damage metallic surfaces, which can lead to equipment damage and system failure.

[0008] Thus, it is important to prevent the formation of deposits and build-up of precipitates in top-pressure recovery turbine systems. Accordingly, there is a needfor improved methods of limiting deposition of precipitates formed from blast furnace gases on the surfaces of top-pressure recovery turbine parts.BRIEF SUMMARY OF THE INVENTION

[0009] Disclosed herein are corrosion inhibitor compositions comprising from about 3 wt.% to about 7 wt.% of a triazole, a solvent comprising methanol, water, ethanol, propanol, or a combination thereof, and optionally a pH adjusting agent, wherein the concentration of triazole is based on the total weight of the triazole, solvent, and pH adjusting agent in the composition.

[0010] The corrosion inhibitor compositions described herein, whereby the corrosion inhibitor composition reduces corrosion rate of equipment in contact with a blast furnace gas condensate.

[0011] Additionally, the corrosion inhibitor compositions described herein can have the blast furnace gas condensate be present in a blast furnace gas pipe.

[0012] The corrosion inhibitor compositions described herein, wherein the blast furnace gas pipe is present in a steel mill.

[0013] Also, the corrosion inhibitor composition can have the solvent comprise ethanol at a concentration from about 10 wt.% to about 40 wt.%, from about 15 wt.% to about 40 wt.%, from about 15 wt.% to about 35 wt.%, from about 15 wt.% to about 30 wt.%, or from about 20 wt.% to about 25 wt.%.

[0014] The corrosion inhibitor compositions described herein can have the solvent comprise water and the water is present at a concentration of from about 25 wt.% to about 60 wt.%, from about 30 wt.% to about 60 wt.%, from about 35 wt.% to about 60 wt.%, or from about 50 wt.% to about 57 wt.%.

[0015] The corrosion inhibitor compositions described herein can have the triazole comprise benzotriazole, tolyltriazole, alkyl triazole, nitrotriazole, or a combination thereof; preferably, the triazole comprises benzotriazole.

[0016] Further, the corrosion inhibitor compositions described herein can have the triazole have a concentration from about 4 wt.% to about 7 wt.% or from about 4 wt.% to about 6 wt.%.

[0017] The corrosion inhibitor compositions can have the composition comprise the pH adjusting agent and the pH adjusting agent comprises cyclohexylamine, morpholine, monoethanolamine (MEA), dimethylethanolamine(DMEA), methoxypropylamine, aqueous ammonia (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), sodium bicarbonate (NaHCOs), trisodium phosphate, or a combination thereof.

[0018] Preferably, the pH adjusting agent comprises cyclohexylamine, sodium hydroxide, or a combination thereof.

[0019] The corrosion inhibitor compositions can have the concentration of the pH adjusting agent be from about 3 wt.% to about 30 wt.%, from about 5 wt.% to about 30 wt.%, from about 8 wt.% to about 25 wt.%, from about 10 wt.% to about 20 wt.%, or from about 12 wt.% to about 15 wt.%.

[0020] The corrosion inhibitor compositions described herein can have the composition further comprise a filming agent.

[0021] The corrosion inhibitor compositions can have the filming agent comprise hexamethylenetetramine, thiourea, sodium nitrite, sodium gluconate, benzalkonium chloride, or a combination thereof.

[0022] The corrosion inhibitor compositions can have the filming agent comprise from about 5 wt.% to about 30 wt.% of the composition, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0023] Additionally, the corrosion inhibitor compositions described herein can have the filming agent comprise from about 5 wt.% to about 20 wt.% of the composition.

[0024] The corrosion inhibitor compositions described herein can have the filming agent comprise from about 2 wt.% to about 10 wt.% of hexamethyleneteramine.

[0025] Also, the corrosion inhibitor compositions can have the filming agent comprise from about 2 wt.% to about 10 wt.% of thiourea.

[0026] The corrosion inhibitor compositions can have the filming agent comprise from about 2 wt.% to about 10 wt.% benzalkonium chloride.

[0027] Additionally, disclosed are methods for inhibiting corrosion in a blast furnace coal gas pipe comprising contacting the corrosion inhibitor compositions described herein with the blast furnace coal gas pipe.

[0028] The methods described herein, wherein the corrosion inhibitor composition is contacted with the blast furnace coal gas pipe at a concentration fromabout 1 gram to about 2000 grams of corrosion inhibitor composition per 10,000 m3of blast furnace gas.

[0029] Other objects and features will be in part apparent and in part pointed out hereinafter.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0030] FIG. 1 is a schematic of a blast furnace dry type cleaning system and a 5 to 1000 g corrosion inhibitor per 10000 cubic meter of blast furnace coal gastop- pressure recovery turbine.DETAILED DESCRIPTION OF THE INVENTION

[0031] Described herein are corrosion inhibitor compositions and methods of using the corrosion inhibitor compositions to reduce corrosion in steel mill blast furnace coal gas pipes. The corrosion inhibitor composition can significantly reduce the corrosion rate in a coal gas pipe contained in a steel mill blast furnace.

[0032] Disclosed herein are corrosion inhibitor compositions comprising from about 3 wt.% to about 7 wt.% of a triazole, a solvent comprising methanol, water, or a combination thereof, and optionally a pH adjusting agent, wherein the concentration of triazole is based on the total weight of the triazole, solvent, and pH adjusting agent in the composition.

[0033] The corrosion inhibitor compositions described herein, whereby the corrosion inhibitor composition reduces corrosion rate of equipment in contact with a blast furnace gas condensate.

[0034] Additionally, the corrosion inhibitor compositions described herein can have the blast furnace gas condensate be present in a blast furnace gas pipe.

[0035] The corrosion inhibitor compositions described herein, wherein the blast furnace gas pipe is present in a steel mill.

[0036] Also, the corrosion inhibitor composition can have the solvent comprise ethanol at a concentration from about 10 wt.% to about 50 wt.%, from about 15 wt.% to about 40 wt.%, from about 20 wt.% to about 35 wt.%, from about 25 wt.% to about 35 wt.%, or about 30 wt.%.

[0037] Additionally, the corrosion inhibitor composition can have the solvent comprise ethanol at a concentration from about 10 wt.% to about 40 wt.%, fromabout 15 wt.% to about 40 wt.%, from about 15 wt.% to about 35 wt.%, from about 15 wt.% to about 30 wt.%, or from about 20 wt.% to about 25 wt.%.

[0038] The corrosion inhibitor compositions described herein can have the solvent comprise water and the water is present at a concentration of from about 5 wt.% to about 40 wt.%, from about 10 wt.% to about 30 wt.%, from about 15 wt.% to about 25 wt.%, or about 20 wt.%.

[0039] Additionally, the corrosion inhibitor compositions described herein can have the solvent comprise water and the water is present at a concentration of from about 25 wt.% to about 60 wt.%, from about 30 wt.% to about 60 wt.%, from about 35 wt.% to about 60 wt.%, or from about 50 wt.% to about 57 wt.%.

[0040] The corrosion inhibitor compositions described herein can have the triazole comprise benzotriazole, tolyltriazole, or a combination thereof; preferably, the triazole comprises benzotriazole.

[0041] Further, the corrosion inhibitor compositions described herein can have the triazole have a concentration from about 3 wt.% to about 6 wt.% or from about 3 wt.% to about 5 wt.%.

[0042] Further, the corrosion inhibitor compositions described herein can have the triazole have a concentration from about 4 wt.% to about 7 wt.% or from about 4 wt.% to about 6 wt.%.

[0043] The corrosion inhibitor compositions can have the composition comprise the pH adjusting agent and the pH adjusting agent comprises cyclohexylamine, morpholine, monoethanolamine (MEA), dimethylethanolamine (DMEA), methoxypropylamine, aqueous ammonia (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), sodium bicarbonate (NaHCOs), trisodium phosphate, or a combination thereof.

[0044] Preferably, the pH adjusting agent comprises cyclohexylamine, sodium hydroxide, or a combination thereof.

[0045] The corrosion inhibitor compositions can have the concentration of the pH adjusting agent be from about 5 wt.% to about 50 wt.%, from about 10 wt.% to about 40 wt.%, from about 20 wt.% to about 40 wt.%, from about 25 wt.% to about 35 wt.%, or about 30 wt.%.

[0046] Additionally, the corrosion inhibitor compositions can have the concentration of the pH adjusting agent be from about 3 wt.% to about 30 wt.%, fromabout 5 wt.% to about 30 wt.%, from about 8 wt.% to about 25 wt.%, from about 10 wt.% to about 20 wt.%, or from about 12 wt.% to about 15 wt.%.

[0047] The corrosion inhibitor compositions described herein can have the composition further comprise a filming agent.

[0048] The corrosion inhibitor compositions can have the filming agent comprise hexamethylenetetramine, thiourea, sodium nitrite, sodium gluconate, benzalkonium chloride, or a combination thereof.

[0049] The corrosion inhibitor compositions can have the filming agent comprise from about 5 wt.% to about 30 wt.% of the composition, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0050] Additionally, the corrosion inhibitor compositions described herein can have the filming agent comprise from about 5 wt.% to about 20 wt.% of the composition.

[0051] The corrosion inhibitor compositions described herein can have the filming agent comprise from about 2 wt.% to about 10 wt.% of hexamethyleneteramine.

[0052] Also, the corrosion inhibitor compositions can have the filming agent comprise from about 2 wt.% to about 10 wt.% of thiourea.

[0053] Additionally, the corrosion inhibitor compositions can have the filming agent comprise from about 2 wt.% to about 10 wt.% of benzalkonium chloride.

[0054] The corrosion inhibitor compositions can have the triazole comprise from about 3 wt.% to about 7 wt.%, the solvent comprise from about 15 wt.% to about 80 wt.%, the filming agent can comprise from about 10 wt.% to about 20 wt.%, and the pH adjusting agent can comprise about 10 wt.% to about 40 wt.%, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0055] Also, the corrosion inhibitor compositions can have the triazole comprise from about 3 wt.% to about 7 wt.%, the solvent comprise from about 30 wt.% to about 80 wt.%, the filming agent can comprise from about 10 wt.% to about 20 wt.%, and the pH adjusting agent can comprise about 3 wt.% to about 30 wt.%, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0056] Additionally, the corrosion inhibitor compositions can have the triazole be benzotriazole and comprise from about 3 wt.% to about 7 wt.%, the solvent beethanol and water and comprise from about 10 wt.% to about 40 wt.% ethanol and from 25 wt.% to about 62 wt.% water, the filming agent comprise from about 2 wt.% to about 10 wt.% hexamethylenetetramine, from about 2 wt.% to about 10 wt.% thiourea, and from about 2 wt.% to about 10 wt.% benzalkonium chloride, and the pH adjusting agent comprise from about 2 wt.% to about 20 wt.% cyclohexylamine and from about 1 wt.% to about 10 wt.% sodium hydroxide, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0057] Also, the corrosion inhibitor compositions can have the triazole be benzotriazole and comprise from about 4 wt.% to about 6 wt.%, the solvent be ethanol and water and comprise from about 25 wt.% to about 35 wt.% ethanol and from about 25 wt.% to about 55 wt.% water, the filming agent comprise from about 3 wt.% to about 8 wt.% hexamethylenetetramine, from about 3 wt.% to about 8 wt.% thiourea, and from about 3 wt.% to about 8 wt.% benzalkonium chloride; and the pH adjusting agent comprise from about 7 wt.% to about 13 wt.% cyclohexylamine and from about 1 wt.% to about 4 wt.% sodium hydroxide; based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0058] The corrosion inhibitor compositions can have the triazole comprise about 5 wt.% benzotriazole, the solvent be ethanol and water and comprise about 30 wt.% ethanol and about 20 wt.% water, the filming agent comprise about 7.5 wt.% hexamethylenetetramine and about 7.5 wt.% thiourea, and the pH adjusting agent can comprise about 30 wt.% cyclohexylamine, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0059] Additionally, the corrosion inhibitor compositions can have the triazole comprise about 5 wt.% benzotriazole, the solvent be ethanol and water and comprise about 20 wt.% ethanol and about 47.5 wt.% water, the filming agent comprise about 5 wt.% hexamethylenetetramine, about 5 wt.% thiourea, and about 5 wt.% benzalkonium chloride; and the pH adjusting agent can comprise about 10 wt.% cyclohexylamine and about 2.5 wt.% sodium hydroxide, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

[0060] Additionally, disclosed are methods for inhibiting corrosion in a blast furnace coal gas pipe comprising contacting the corrosion inhibitor compositions described herein with the blast furnace coal gas pipe.

[0061] The methods described herein, wherein the corrosion inhibitor composition is contacted with the blast furnace coal gas pipe at a concentration from about 5 grams to about 2000 grams corrosion inhibitor composition (composition contains approximately 50%-55% actives) or about 2.5 grams to about 1000 grams actives in the composition per 10,000 m3of blast furnace gas.

[0062] The corrosion inhibitor compositions described herein can form a film on a surface.

[0063] The corrosion inhibitor compositions can be used in methods of inhibiting corrosion by contacting the corrosion inhibitor composition with a surface in contact with an aqueous medium comprising ammonia, hydrochloric acid, ammonium chloride, sulfuric acid, nitrogen, carbon dioxide, carbon monoxide, sulfur dioxide, hydrogen, hydrogen sulfide, hydrogen cyanide, or a combination thereof.

[0064] Preferably, in the methods of inhibiting corrosion, the aqueous medium comprises ammonium chloride, hydrochloric acid, or a combination thereof.

[0065] Additionally, in the methods of inhibiting corrosion described herein, the surface is a metal surface. In particular, the metal surface comprises carbon steel.

[0066] In the methods of inhibiting corrosion described herein, the corrosion inhibitor compositions can form a protective layer between the metal surface and the corrosive media.

[0067] Additionally, in the methods of inhibiting corrosion described herein, the equipment is contained in a smelting system comprising a blast furnace.

[0068] It is preferable that the effective amount of the corrosion inhibitor compositions is administered at dosages which provide for anywhere from 1 ppm to about 1 ,000 ppm active compounds based on the total amount of blast furnace gas fluids being treated by these compositions. Preferably the dosage ranges from about 2 to about 500 ppm active ingredient based on the refinery stream being treated, and most preferably the dosage range from about 5 to about 200 ppm.

[0069] To obtain optimum results, it is preferred to add the above dosages at the higher end initially and then maintenance dosages can be dropped to the lower end of the concentration mentioned above. As an example, a system would be expected to be optimized by treating with approximately 250-500 ppm of the active compounds in the corrosion inhibitor compositions based on the blast furnace gas fluid being treated, for the initial 24-72 hours of operation. Thereafter, the dosagetreatment rate would be effectively dropped over a period of from 1 to about 10 days to a maintenance level ranging between from about 1 ppm to about 100 ppm, preferably from about 5 to about 50 ppm of the actives in the composition, based on the blast furnace gas fluid being treated.

[0070] A fluid or gas treated with a corrosion inhibitor composition can be at any selected temperature, such as ambient temperature or an elevated temperature. The fluid (e.g., liquid hydrocarbon) or gas can be at a temperature of from about 40 °C to about 250 °C. The fluid or gas can be at a temperature of from -50 °C to 300 °C, 0 °C to 200 °C, 10 °C to 100 °C, or 20 °C to 90 °C. The fluid or gas can be at a temperature of 22 °C, 23 °C, 24 °C, 25°C, 26 °C, 27 °C, 28 °C, 29 °C, 30 °C, 31 °C, 32 °C, 33 °C, 34 °C, 35 °C, 36 °C, 37 °C, 38 °C, 39 °C, or 40 °C. The fluid or gas can be at a temperature of 85 °C, 86 °C, 87 °C, 88 °C, 89 °C, 90 °C, 91 °C, 92 °C, 93 °C, 94 °C, 95 °C, 96 °C, 97 °C, 98 °C, 99 °C, or 100 °C.

[0071] The corrosion inhibitor composition can be introduced into a fluid or gas by any appropriate method for ensuring dispersal through the fluid or gas.

[0072] The corrosion inhibitor composition can be added at a point in a flow line upstream from the point at which corrosion prevention is desired.

[0073] The corrosion inhibitor composition can be injected using mechanical equipment such as chemical injection pumps, piping tees, injection fittings, atomizers, quills, and the like.

[0074] The corrosion inhibitor composition can be introduced with or without one or more additional polar or non-polar solvents depending upon the application and requirements.

[0075] The corrosion inhibitor composition can be introduced into a liquid and mixed.

[0076] The corrosion inhibitor composition can be injected into a gas stream as an aqueous or non-aqueous solution, mixture, or slurry.

[0077] The corrosion inhibitor composition can be applied continuously, in batch, or a combination thereof. The corrosion inhibitor composition doses can be continuous to prevent corrosion. The corrosion inhibitor composition doses can be intermittent (i.e. , batch treatment) or the corrosion inhibitor composition doses can be continuous / maintained and / or intermittent to inhibit corrosion.

[0078] The corrosion inhibitor compositions can be injected into the blast furnace gas in a top-pressure recovery turbine system. In particular, the corrosion inhibitor composition can be injected into the top-pressure recovery turbine system as a liquid using a spraying device such as an injection quill or an injection nozzle.

[0079] Also, the corrosion inhibitor composition can be injected into the toppressure recovery turbine system as a gas using an injection quill or an injection nozzle.

[0080] In some cases, an inert gas such as nitrogen or argon can be used as a carrier gas for injection of the liquid corrosion inhibitor composition into the toppressure recovery turbine system. Additionally, the corrosion inhibitor composition can be added to a top-pressure recovery turbine by injecting the corrosion inhibitor composition as an aqueous liquid into blast furnace gas in the top-pressure recovery turbine.

[0081] Also, the top-pressure recovery turbine can comprise an injection port or inlet. Preferably, the injection port is at a temperature of from about 35 °C to about 60 °C. More preferably, the injection port is at a temperature of from about 50 °C to about 60 °C.

[0082] The corrosion inhibitor composition can be added to the top-pressure recovery turbine in any amount. The corrosion inhibitor composition can be added to the top-pressure recovery turbine and is present in the top-pressure recovery turbine at a concentration of from about 0.001 ppm to about 10,000 ppm. Thus, the corrosion inhibitor composition is added to the top-pressure recovery turbine and is present in the top-pressure recovery turbine at a concentration of from about 0.001 ppm to about 10,000 ppm, 0.01 ppm to about 10,000 ppm, from about 0.1 ppm to about 10,000 ppm, from about 1 ppm to about 10,000 ppm, from about 10 ppm to about 10,000 ppm, from about 100 ppm to about 10,000 ppm, from about 150 ppm to about 10,000 ppm, from about 0.001 ppm to about 5,000 ppm, from about 0.01 ppm to about 5,000 ppm, from about 0.1 ppm to about 5,000 ppm, from about 1 ppm to about 5,000 ppm, from about 10 ppm to about 5,000 ppm, from about 0.001 ppm to about 2500 ppm, from about 0.01 ppm to about 2500 ppm, from about 0.1 ppm to about 2500 ppm, from about 1 ppm to about 2500 ppm, from about 10 ppm to about 2500 ppm, from about 0.001 ppm to about 1000 ppm, from about 0.01 ppm to about 1000 ppm, from about 0.1 ppm to about 1000 ppm, from about 1 ppm to about 1000ppm, from about 0.001 ppm to about 500 ppm, from about 0.01 ppm to about 500 ppm, from about 0.1 ppm to about 500 ppm, from about 1 ppm to about 500 ppm, from about 0.001 ppm to about 300 ppm, from about 0.01 ppm to about 300 ppm, from about 0.1 ppm to about 300 ppm, from about 1 ppm to about 300 ppm, from about 0.001 ppm to about 250 ppm, from about 0.01 ppm to about 250 ppm, from about 0.1 ppm to about 250 ppm, or from about 1 ppm to about 250 ppm.

[0083] The corrosion inhibitor composition can be prepared by adding the pH adjusting agent to a vessel and also adding a solvent (e.g., ethanol) to the vessel. After the pH adjusting agent and solvent are mixed, a filming agent is added slowly and the mixture is stirred until all components are dissolved in the solvent. An additional filming agent can be added to the mixture, followed by addition of a triazole and the mixture is stirred until all the components are dissolved at each addition of another agent. After the mixture is completely dissolved, the balance of the solvent (e.g., water) is added to the vessel.

[0084] "Blast furnace gas" or "top gas" refers to gas produced by a blast furnace. Nonlimiting examples of components of blast furnace gas include ammonia, hydrochloric acid, sulfuric acid, nitrogen, carbon dioxide, carbon monoxide, sulfur dioxide, hydrogen, hydrogen sulfide, hydrogen cyanide, and water vapor.

[0085] "Blast furnace gas solid" refers to a solid formed from one or more components of a blast furnace gas. For example, blast furnace gas solids may form via reaction of a basic blast furnace gas and an acidic blast furnace gas. Non-limiting examples of blast furnace gas solids include ammonium salts such as ammonium chloride and ammonium sulfate.

[0086] "Dry-type top-pressure recovery turbine" refers to a top-pressure recovery turbine that employs a dry-type dust collector to purify blast furnace gas (e.g., remove dust). "Injection quill" refers to a device used to inject one or more chemicals into the center of a line or pipe.

[0087] "Metal-producing process" refers to any process that utilizes a blast furnace to produce metal. Non-limiting examples of such processes include an iron producing process, a steel producing process, copper producing process, lead producing process, nickel producing process, aluminum producing process, and zinc producing process.

[0088] "Top-pressure recovery turbine" or "TRT" refers to a turbine device capable of extracting energy from blast furnace gas. Equivalent terms include "top- gas-pressure recovery turbine," "top-gas recovery turbine," "pressure recovery turbine," "blast furnace gas pressure recovery turbine," "blast furnace gas toppressure recovery turbine," "furnace top pressure recovery turbine," and the like.

[0089] Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.EXAMPLES

[0090] The following non-limiting examples are provided to further illustrate the invention.

[0091] The components of the corrosion inhibitor compositions are benzotriazole (Component T1 ), tolyltriazole (Component T2), sodium hydroxide (Component P1 ), cyclohexylamine (Component P2), morpholine (Component P3), monoethanolamine (Component P4), dimethylethanolamine (Component P5), methoxypropylamine (Component P6), aqueous ammonium (Component P7), potassium hydroxide (Component P8), sodium carbonate (Component P9), sodium bicarbonate (Component P10), trisodium phosphate (Component P11), ethanol (Component S1), water (Component S2), hexamethylenetetramine (Component F1 ), thiourea (Component F2), benzalkonium chloride (Component F3), sodium nitrite (Component F4), and sodium gluconate (Component F5).Example 1 : Corrosion Performance

[0092] Each of eight bottles was prepared by adding 0.5 L water, a stock solution was added according to blast furnace gas condensate composition and the treatment corrosion inhibitor composition was added. The coupon was added and the test mixture was stirred and the bottle was sealed. The stock solution was prepared by adding hydrochloric acid (HCI), ammonium chloride (NH4CI), and sodium chloride (NaCI) to demineralized water to a concentration of 1800 ppm HCI, 500 ppm NH4CI, and 5000 ppm NaCI.

[0093] The bottle was put into a water bath and the temperature was set to about 50 °C. A stirrer was placed in the water bath and stirring was started.

[0094] After 24 hours, the coupons were removed from the bottles, the water on the surface was wiped off, and the coupons were dried in an approximately 60 °C oven for 2 hours, then weighed and pictures obtained.

[0095] The coupons were cleaned with diluted hydrochloric acid (2.4 mol / L) with hexamethylenetetramine (8 g / L) as a corrosion inhibitor; then the coupons were rinsed with D.l. Water, the surface water was absorbed, and the coupons were rinsed with acetone, and then the coupons were placed into a 60 °C oven for 2 hours and then weighed.

[0096] Corrosion inhibition rate was calculated using the weight loss and surface area of the coupons.

[0097] The test corrosion inhibitor composition B and its corrosion inhibition test results are detailed below.Corrosion Inhibitor Composition BCorrosion Inhibitor Results for Corrosion Inhibitor Compositions A and B

[0098] Corrosion Inhibitor Composition A was 32 wt.% aqueous sodium hydroxide solution. A significantly smaller amount (200 ppm) of Corrosion InhibitorComposition B was needed to get a similar corrosion inhibition rate (83.5% vs. 82.96%) as compared to Corrosion Inhibitor Composition A at 15,000 ppm.

[0099] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional steps or components. The singular forms “a,” “and,” “the” and “said” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of” and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0100] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

[0101] As various changes could be made in the above compositions and processes without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:1 . A corrosion inhibitor composition comprising from about 3 wt.% to about 7 wt.% of a triazole, a solvent comprising methanol, water, or a combination thereof, and optionally a pH adjusting agent, wherein the concentration of triazole is based on the total weight of the triazole, solvent, and pH adjusting agent in the composition.

2. The corrosion inhibitor composition of claim 1 , whereby the corrosion inhibitor composition reduces corrosion rate of equipment in contact with a blast furnace gas condensate.

3. The corrosion inhibitor composition of claim 2, wherein the blast furnace gas condensate is present in a blast furnace gas pipe.

4. The corrosion inhibitor composition of claim 3, wherein the blast furnace gas pipe is present in a steel mill.

5. The corrosion inhibitor composition of any one of claims 1 to 4, wherein the solvent comprises ethanol at a concentration from about 10 wt.% to about 40 wt.%.

6. The corrosion inhibitor composition of any one of claims 1 to 4, wherein the solvent comprises ethanol at a concentration from about 15 wt.% to about 40 wt.%.

7. The corrosion inhibitor composition of any one of claims 1 to 4, wherein the solvent comprises ethanol at a concentration from about 15 wt.% to about 35 wt.%.

8. The corrosion inhibitor composition of any one of claims 1 to 4, wherein the solvent comprises ethanol at a concentration from about 15 wt.% to about 30 wt.%.

9. The corrosion inhibitor composition of any one of claims 1 to 4, wherein the solvent comprises ethanol at a concentration of from about 20 wt.% to about 25 wt.%.

10. The corrosion inhibitor composition of any one of claims 1 to 9, wherein the solvent comprises water and the water is present at a concentration of from about 25 wt.% to about 60 wt.%.11 . The corrosion inhibitor composition of any one of claims 1 to 9, wherein the solvent comprises water and the water is present at a concentration of from about 30 wt.% to about 60 wt.%.

12. The corrosion inhibitor composition of any one of claims 1 to 9, wherein the solvent comprises water and the water is present at a concentration of from about 35 wt.% to about 60 wt.%.

13. The corrosion inhibitor composition of any one of claims 1 to 9, wherein the solvent comprises water and the water is present at a concentration of from about 50 wt.% to about 57 wt.%.

14. The corrosion inhibitor composition of any one of claims 1 to 13, wherein the triazole comprises benzotriazole, tolyltriazole, or a combination thereof.

15. The corrosion inhibitor composition of claim 14, wherein the triazole comprises benzotriazole.

16. The corrosion inhibitor composition of any one of claims 1 to 15, wherein the triazole has a concentration from about 4 wt.% to about 7 wt.%.

17. The corrosion inhibitor composition of claim 16, wherein the triazole has a concentration from about 4 wt.% to about 6 wt.%.

18. The corrosion inhibitor composition of any one of claims 1 to 17, wherein the composition comprises the pH adjusting agent and the pH adjusting agent comprises cyclohexylamine, morpholine, monoethanolamine (MEA), dimethylethanolamine (DMEA), methoxypropylamine, aqueous ammonia (NH4OH), sodium hydroxide(NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), sodium bicarbonate (NaHCOs), trisodium phosphate, or a combination thereof.

19. The corrosion inhibitor composition of claim 18, wherein the pH adjusting agent comprises cyclohexylamine, sodium hydroxide, or a combination thereof.

20. The corrosion inhibitor composition of claim 18 or 19, wherein the concentration of the pH adjusting agent is from about 3 wt.% to about 30 wt.%.21 . The corrosion inhibitor composition of claim 20, wherein the concentration of the pH adjusting agent is from about 5 wt.% to about 30 wt.%.

22. The corrosion inhibitor composition of claim 20, wherein the concentration of the pH adjusting agent is from about 8 wt.% to about 25 wt.%.

23. The corrosion inhibitor composition of claim 20, wherein the concentration of the pH adjusting agent is from about 10 wt.% to about 20 wt.%.

24. The corrosion inhibitor composition of claim 20, wherein the concentration of the pH adjusting agent from about 12 wt.% to about 15 wt.%.

25. The corrosion inhibitor composition of any one of claims 1 to 24, wherein the composition further comprises a filming agent.

26. The corrosion inhibitor composition of claim 25, wherein the filming agent comprises hexamethylenetetramine, thiourea, sodium nitrite, sodium gluconate, benzalkonium chloride, or a combination thereof.

27. The corrosion inhibitor composition of claim 25 or 26, wherein the filming agent comprises from about 5 wt.% to about 30 wt.% of the composition, based on the total weight of the triazole, solvent, pH adjusting agent, and filming agent.

28. The corrosion inhibitor composition of claim 27, wherein the filming agent comprises from about 5 wt.% to about 20 wt.% of the composition.

29. The corrosion inhibitor composition of claim 27 or 28, wherein the filming agent comprises from about 2 wt.% to about 10 wt.% of hexamethyleneteramine.

30. The corrosion inhibitor composition of any one of claims 27 to 29, wherein the filming agent comprises from about 2 wt.% to about 10 wt.% of thiourea.31 . The corrosion inhibitor composition of any one of claims 27 to 30, wherein the filming agent comprises from about 2 wt.% to about 10 wt.% of benzalkonium chloride.

32. A method for inhibiting corrosion in a blast furnace coal gas pipe comprising contacting the corrosion inhibitor composition of any one of claims 1 to 30 with the blast furnace coal gas pipe.

33. The method of claim 31 , wherein the corrosion inhibitor composition is contacted with the blast furnace coal gas pipe at a concentration from about 1 grams to about 2000 grams of corrosion inhibitor composition per 10,000 m3of blast furnace coal gas.

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