KR101875039B1 - Fuel Additives and Fuel Additives Supply System for Coal Boilers Using Chemical Cleaning Wastewater - Google Patents

Abstract

The present invention relates to fuel additives and a fuel additives supply system for coal boilers using chemical cleaning wastewater, which can effectively remove sulfur oxide gas from a coal boiler by reusing the chemical cleaning wastewater. The fuel additives for the coal boilers according to the present invention comprises: a main ingredient consisting of Fe(III)-(NH4)2-EDTA; and a mixture consisting of a magnesium carboxylate compound.

Description

TECHNICAL FIELD [0001] The present invention relates to a chemical additive and a fuel additive,

The present invention relates to a fuel additive for a coal boiler using chemical wastewater and a fuel additive supply system for the coal boiler. More particularly, the present invention relates to a fuel additive for a boiler, To a fuel additive for a coal boiler using chemically cleaned wastewater that prevents corrosion of the outer surface of the tube and a system for supplying the fuel additive.

Generally, a boiler of a coal-fired thermal power plant is a coal-fired boiler with low ashfusiontemperatures, which causes fouling and slagging in the boiler superheater and reheat tube. Such fouling and slinging gradually grow to become a large clinker.

Such a large clinker is liable to fall into the boiler tube or the like due to its weight, and the boiler tube is ruptured, thereby causing a serious accident such as an explosion during operation of the boiler.

Sulfur dioxide gas (SO2), sulfur trioxide gas (SO3) and hydrogen sulfide gas (H2S) are generated while sulfur (S) contained in coal is burned in the boiler.

Of these, sulfur dioxide gas and sulfur trioxide gas (hereinafter referred to as "sulfur oxide gas") cause sulfurization in generating facilities such as boiler tubes and ducts, and some sulfur dioxide gases are discharged into the atmosphere, At the same time, it causes acid rain.

However, while sulfur dioxide gas is mostly removed using a desulfurizer, the sulfur trioxide gas can not be removed from the desulfurizer, causing low temperature corrosion of the air preheater and exhaust gas duct, and producing a blue flume in the stack as it is vented to the atmosphere .

In addition, the hydrogen sulfide gas causes sulfide corrosion on the outer surface of the boiler water wall of a coal-fired power plant having a combustion temperature of about 350 to 450 ° C. This corrosion reaction is repeated as the hydrogen sulfide gas forms a porous non-adherent sulfide slag on the outer surface of the water pipe, and then easily tears off from the outer surface of the water pipe wall.

In order to solve the above problems, conventionally, a clinker inhibitor or a sulfur trioxide generation inhibitor is used. Such a conventional anticaking agent for inhibiting clinker and sulfur trioxide is a magnesium oxide powder having a particle size of about 10 to 40 탆, a magnesium hydroxide powder, And a slurry state product in which the powder and the dispersant are mixed with a liquid such as oil.

However, these products have a problem of low reactivity with sulfur oxide gas because of their large particle size.

Therefore, it is required to develop a fuel additive for a boiler and a fuel additive supply system for a coal-fired power plant that prevents corrosion of the outer surface of a tube of the boiler by removing sulfur oxide gas contained in the exhaust gas discharged from the boiler of the coal-fired power plant.

KR 10-2016-0027667 A (Mar. 10, 2016) KR 10-2004-0100596 A (December 02, 2004) KR 10-1772880 B1 (Aug. 24, 2017)

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a method and apparatus for effectively removing sulfur oxide gas from a coal boiler by reusing chemical cleaning wastewater A fuel additive for a coal boiler using chemical cleaning wastewater, and a system for supplying the fuel additive.

In order to achieve the above object, the present invention provides a fuel additive for a coal boiler using chemical cleaning wastewater, comprising: (a) a support made of Fe (III) - (NH4) 2-EDTA; And

A mixture comprising a magnesium carboxyl compound; .

In the present invention, the magnesium carboxylate is dissolved in an aqueous solution containing 0.5 to 1.6 moles of citric acid, 1.6 to 4.8 moles of acetic acid and 2.1 to 6.6 moles of formic acid in an amount of 3.6 to 4.6 moles of magnesium hydroxide, and a magnesium concentration of 2.9 mol / L or more In order to achieve the above object.

In addition, the present invention relates to a process for preparing a magnesium carboxylate by dissolving 2.5 to 3.8 mol of magnesium oxide in an aqueous solution containing 0.5 to 1.6 mol of citric acid, 1.6 to 4.8 mol of acetic acid and 2.1 to 6.6 mol of formic acid, Or more.

Meanwhile, the fuel additive supply system for the coal boiler using the chemical cleaning wastewater according to the present invention includes: a main tank in which chemical cleaning wastewater is stored; A concentrating tank for heating the chemical washing wastewater supplied from the main tank with a heater to produce a concentrate; A mixing tank connected to the concentrating tank and supplied with the concentrate prepared in the concentrating tank; A mixer tank connected to the mixing tank and supplying a predetermined amount of the mixed agent to the mixing tank; A storage tank connected to the mixing tank and supplied with the mixed fuel additive in the mixing tank and stored; And an injector for injecting the fuel additive stored in the storage tank through a fuel inlet of the boiler; And a control unit.

Further, the present invention is characterized in that the concentrate concentrated in the concentrating tank contains Fe (III) - (NH4) 2-EDTA, and the mixed agent stored in the mixed tank is a magnesium carboxyl compound.

According to the present invention, the fuel additive is prepared by mixing the organic acid chemical washing wastewater used in the coal-fired power plant with the blending agent so that the chemical washing wastewater is reused and the cost of processing the chemical washing wastewater, .

In addition, since the magnesium carboxylate is composed of an ionic material having a particle size smaller than that of the conventional magnesium hydroxide or magnesium oxide, when the same amount as that of the conventional fuel additive is added to the fuel, Thereby further suppressing the generation of the sulfur trioxide gas, and at the same time, removing the sulfur gas.

In addition, since the magnesium carboxyl compound generates a lot of microcracks in the coal fly ash, the occurrence of large clinker is prevented.

In addition, since the iron component in the chemical cleaning wastewater is recovered as a chelate compound and reused as a fuel additive for a boiler of a coal-fired power plant, the cost for treating chemical wastewater can be reduced, which is economical advantage.

1 is a view showing an example of a fuel additive supply system for a coal boiler using chemical cleaning wastewater according to the present invention.
2 is a sectional view showing an example of a main tank according to the present invention.
3 is a sectional view showing an example of a concentration tank according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a fuel additive for a coal boiler using a chemical cleaning wastewater capable of effectively removing sulfur oxide gas from a coal boiler by reusing chemical wastewater and a system for supplying the fuel additive. A mixing tank 30, a mixing tank 40, a storage tank 50, and a spraying device 60 as shown in the drawing.

As shown in FIG. 1, the main tank 10 is provided with an inlet 10A for introducing the chemical washing wastewater into the main tank 10, And a first discharge port 10B through which the chemical cleaning wastewater stored therein is discharged.

A washing waste liquid inflow line L1 to which the chemical washing wastewater discharged from a cleaning device or the like is supplied is connected to the inlet 10A and a wastewater supply valve V1 'is provided on the washing waste inflow line L1.

At this time, the wastewater supply valve V1 'is configured to be automatically opened and closed according to a water level detected by a water level sensor (not shown) installed in the main tank 10, To detect the highest water level and the lowest water level within the range set in the air conditioner.

Further, a main supply line L2 for supplying the chemical cleaning wastewater to the concentration tank 20 to be described later is connected to the first discharge port 10B.

The main tank 10 having the above-described configuration is configured such that the chemical components such as iron contained in the chemical cleaning wastewater are agglomerated and supplied to the concentration tank 20 before the chemical cleaning wastewater is supplied to the concentration tank 20 Whereby the concentrate obtained in the concentrating tank 20 contains a larger amount of useful components.

As described above, the main tank 10 according to the present invention can be provided with a structure for more easily agglomerating useful components used as a fuel additive from the chemical cleaning wastewater. As shown in FIG. 2, The first and second diaphragms 12 and 13 are spaced apart from each other by a predetermined distance while being spaced apart from each other by a predetermined distance. The lower end of the first diaphragm 12 is spaced apart from the bottom of the main tank 10, Is spaced apart from the upper surface of the main tank (10). A filter (F) is installed in the spaced space between the first and second diaphragms (12, 13).

The inlet 10A is provided so as to pass through an upper portion of the outer surface of the main tank 10 facing the first diaphragm 12 and the first outlet 10B is connected to the first and second diaphragms 12, As shown in FIG. At this time, the bottom of the main tank 10 is formed to be inclined downward to a predetermined width so as to face the first discharge port 10B.

A second outlet 10C is formed through the lower portion of the outer surface of the main tank 10 facing the second diaphragm 13. A discharge line L1 'is connected to the second outlet 10C, And an inspection port 11 for maintenance of the filter F provided inside is provided on the upper surface of the main tank 10.

(Not shown) for reusing the chemical cleaning wastewater is connected to the discharge line L1 'and a discharge pump (not shown) for discharging the chemical cleaning wastewater in the main tank 10 P1) are installed.

The main tank 10 having the above-described structure is configured such that an appropriate amount of the chemical cleaning wastewater is supplied to the inside of the main tank 10 through the washing waste liquid inflow line L1, and at the same time, The chemical cleaning wastewater in the main tank 10 is supplied to the chemical cleaning wastewater reuse apparatus through the line L1 '.

In this process, useful components such as iron, which are contained in the chemical cleaning wastewater, are prevented from passing through the filter F, and are accumulated in the main tank 10 continuously.

After the chemical cleaning wastewater is supplied to the waste water reuse apparatus via the main tank 10 for a predetermined period of time as described above, the inlet 10A and the second discharge outlet 10C are closed and the main discharge is connected to the first discharge outlet 10B The first valve V1 installed on the line L2 is opened so that a predetermined amount of the chemical cleaning wastewater stored in the main tank 10 through the first outlet 10B and a large amount of useful components are introduced into the concentrating tank 20, .

The concentrating tank 20 heats a predetermined amount of the chemical washing wastewater supplied from the main tank 10 to form a concentrate. The concentrating tank 20 is a device for concentrating the chemical washing wastewater easily at a low temperature, A concentrator is used.

3, the concentrating tank 20 includes an enrichment section 20A for storing the chemical cleaning wastewater therein, a heating section 20A located below the enrichment section 20A for heating the chemical washing wastewater, And a tank 20B having a double structure.

A heater 21 for heating the chemical cleaning wastewater stored in the thickening section 20A is provided at one side of the heating section 20B and the thickening section 20A is provided with a stirrer 22 for stirring the chemical cleaning wastewater at an appropriate speed, The chemical cleaning wastewater stored in the concentrating unit 20A is agitated at an appropriate speed by the agitator 22 and the heat is uniformly transferred to shorten the time required for concentrating the chemical wastewater.

The agitator 22 includes a stirring shaft 22A connected to the rotation shaft of the motor and vertically installed in the concentrating section 20A and a stirring blade 22B provided on the stirring shaft 22A for stirring the chemical washing wastewater And a discharge blade 22C provided at the lower end of the stirring shaft 22A for pressurizing and discharging the concentrated liquid to the concentrated liquid supply line L3.

Here, the discharge vane 22C is constituted by a spiral or inclined wing so as to push the concentrated liquid toward the concentrated liquid supply line L3 by the rotation operation, and the outer wing portion 22C 'of the discharge vane 22C (Not shown) connected to the concentrated liquid feed line L3, and the inner wing portion 22C " is formed so as to be inclined so as to be closer to the inner bottom surface of the enrichment tank 20 than the upper portion, .

The heated portion 20B on the opposite side of the heater 21 is provided with a rectangular box-shaped warm air storage portion 21A having an appropriate accommodation space therein. Inside the warm air storage portion 21A, (Not shown) that is automatically opened and closed in accordance with the internal pressure of the valve body 21A.

The outer surface of the concentrated liquid supply line L3 is provided with a preheating portion 21B which is communicated with the hot air storage portion 21A and supplied with hot air stored in the hot air storage portion 21A through the relief valve. At this time, a plurality of flow path forming plates 21B 'are provided in the preheating portion 21B, and a plurality of flow path forming plates 21B' form a meandering flow path.

When the heat generated in the heater 21 is heated by the chemical warming wastewater stored in the thickening section 20A and then discharged, the hot air storage section 21A and the preheating section 21B, 21A for a predetermined period of time, and a suitable amount of warm air is discharged through the preheating section 21B according to the pressure, whereby the chemical cleaning wastewater supplied to the concentration tank 20 through the concentrated liquid supply line L3 is preheated The heat energy required to heat the chemical cleaning wastewater through the heater 21 is saved.

A vacuum generator 23 and a vacuum valve 23A are provided at one side of the concentrating section 20A for extracting the air inside the concentrating section 20A to the outside to lower the pressure. The chemical cleaning wastewater is heated by the heater 21 while the internal air of the unit 20A is taken out to the outside and is depressurized, so that the chemical cleaning wastewater easily evaporates even at a relatively low temperature and is rapidly concentrated.

A water level sensor (not shown) or a water level meter is installed in the concentrating part 20A, and the concentration is progressed or stopped by the level of the chemical washing wastewater sensed by the water level sensor or the water level meter.

At this time, if the level of the chemical cleaning wastewater stored in the concentrating section 20A is lowered to 20% when the maximum water level is taken as 100%, the heating of the chemical washing wastewater is stopped, The valve V2 is opened to supply the concentrated liquid to the mixing tank 30 to be described later.

The mixing tank 30 mixes the concentrate supplied from the concentrating tank 20 with the mixed agent supplied from the mixer tank 40 to be described later. In this mixing tank 30, There is provided an agitator 31 for mixing the concentrate supplied with the inside with the mixing agent.

The mixing tank 30 is connected to the storage tank 50 to be described later so that the fuel additive mixed in the mixing tank 30 is supplied to and stored in the storage tank 50.

The mixture tank 40 is a tank for supplying a certain amount of a mixture to the mixing tank 30 and a magnesium carboxyl compound (or magnesium carboxylate) is prepared as a mixture in the mixture tank 40.

1, the mixture tank 40 and the mixing tank 30 are connected by a mixing agent supply line L4 and the mixture tank 40 is provided on the mixing agent supply line L4, A feed pump P2 for feeding the mixed material stored in the mixing tank 30 is provided.

A heater 41 for heating the mixture is installed on the lower side of the mixer tank 40 and a stirrer 42 for mixing the mixer is installed on the other side of the lower side of the mixer tank 40.

A charging tank 43 for charging magnesium hydroxide or magnesium oxide is provided at a predetermined distance from the mixing tank 40. The charging tank 43 is connected to the mixing tank 40 .

At this time, a sensor 44 for detecting an input amount of magnesium hydroxide or magnesium oxide and a fourth valve V4 for controlling the opening and closing of the flow passage are provided on the raw material input line L5.

In this mixed tank 40, a certain amount of an aqueous solution containing 0.5 to 1.6 mol of citric acid, 1.6 to 4.8 mol of acetic acid and 2.1 to 6.6 mol of formic acid is stored. To this aqueous solution is added 3.6 to 4.6 mol of magnesium hydroxide or 2.5 to 3.8 mol of magnesium oxide And the magnesium concentration is 2.9 mol / L or more to prepare a mixture.

At this time, a concentration meter (not shown) for measuring the magnesium concentration is installed in the mixed tank 40, and the opening and closing operation of the fourth valve V4 is automatically controlled according to the concentration detected by the concentration meter, A predetermined amount of magnesium hydroxide or magnesium oxide is supplied from the adsorbent 43.

The storage tank 50 stores the manufactured fuel additive once the fuel additive is properly mixed with the concentrate and the mixture in the mixing tank 30. This storage tank 50 is shown in FIG. As shown in the figure, a pipe (not shown) for supplying the fuel additive manufactured from the mixing tank 30 is provided at one side thereof, and a fuel additive line (not shown) for introducing the fuel additive stored in the storage tank 50 into the boiler (L6).

On the fuel addition line L6, there is provided a feed pump P3 for feeding the fuel additive stored in the storage tank 50 to the injection device described later.

Further, the storage tank 50 is provided with a sensor (not shown) for sensing the amount of the fuel additive stored therein. When the fuel additive stored in the storage tank 50 is reduced by a predetermined amount or less, And the pump is operated to supply the chemical cleaning wastewater and the mixture to the fuel additive so that the fuel additive is always stored in the storage tank 50 and the fuel additive is always maintained.

The injector 60 injects the fuel additive that is provided at the tip of the fuel adding line L6 and supplied through the injecting pump P3 to the inside of the boiler. By this injecting device 60, The gas will react more easily and quickly.

Hereinafter, the fuel additive injected into the boiler through the fuel additive supply system for the coal boiler using the chemical cleaning wastewater according to the present invention will be described in more detail.

Fe (III) - (NH4) 2-EDTA remains as a major component in the concentrate of the chemical cleaning wastewater, and these components are burned in the boiler and the Fe + Fe 2 O 3 Melting Point: 1,539 ~ 1,565 ° C) powder.

The resulting iron oxide powder prevents the formation of large clinker because it breaks the slagging and fouling occurring in the slagging and fouling occurring in the low melting point fly ash by forming microcracks. At the same time, the sulfur (S) And iron oxide powder are directly reacted.

In addition, since EDTA bound to Fe (III) - (NH4) 2-EDTA is an organic compound, a calorific value of about 1,065 kcal / mol is generated in the combustion in a boiler. As a result, generation of sulfur trioxide gas is suppressed, In addition to the original function of the fuel additive for the purpose of removal, it also functions as an auxiliary fuel.

In addition, the ammonia gas generated by the combustion of Fe (III) - (NH4) 2-EDTA in the boiler is reused as a reducing agent to reduce nitrogen oxides in the denitrification plant of the thermal power boiler.

The following formula (1) is a reaction formula in which a magnesium carboxyl compound is produced.

And Formula 2 is a reaction formula of sulfur and fuel additive contained in coal.

The formula (3) is a reaction formula in which the magnesium carboxyl compound in the coal-fired boiler suppresses the generation of sulfur trioxide

In general, sulfur dioxide must be present in the presence of a catalyst (vanadium pentoxide) before it can be oxidized to sulfur trioxide gas. A small amount of vanadium contained in coal is oxidized to vanadium pentoxide in the combustion of coal to act as a catalyst, The carboxyl compound is injected and converted into a compound of 3MgOV2O5 (no catalyst), so that the catalyst function is prevented.

Thus, the magnesium carboxyl compound is burned in a boiler of a coal-fired power plant to produce magnesium oxide (MgO), and magnesium oxide (MgO) thus produced has a high melting point of about 2,850 DEG C, which is an excellent clinker generation inhibitor.

Industrial Applicability As described above, the present invention provides fuel additive by mixing organic acid chemical wastewater used in a coal-fired power plant with an additive, thereby improving the cost of treating chemical wastewater by reusing chemical wastewater, Cost savings.

In addition, since the magnesium carboxylate is an ionic substance having a particle diameter smaller than that of the conventional magnesium hydroxide or magnesium oxide, when the same amount as that of the conventional fuel additive is added to the fuel, the number of particles is relatively increased, As a result, the generation of sulfur trioxide gas is suppressed and the removal efficiency of sulfide gas is excellent, and the particle surface of the magnesium carboxyl compound is very wide, so that a lot of microcracks are generated in the fly ash clump, thereby preventing generation of large clinker.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. It is to be understood that the scope of the present invention should not be interpreted as being limited only by the scope of the present invention and that the scope of the present invention should not be construed to be interpreted to limit the scope of the present invention. .

10, 10 ': Main tank 10A: Inlet
10B: first outlet 10C: second outlet
11: inspection hole 12: first diaphragm
13: second diaphragm 20: enrichment tank
20A: thickening section 20B: heating section
21: heater 21A: hot air storage unit
21B: preheating portion 21B ': flow path forming plate
22: stirrer 22A: stirring shaft
22B: stirring wing 22C: discharge wing
22C ': outer wing portion 22C'': inner wing portion
23: Vacuum generator 23A: Vacuum valve
30: mixing tank 31: stirrer
40: mixture tank 41: heater
42: stirrer 43: input tank
44: Sensor 50: Storage tank
60: Injection device F: Filter
L1: Waste liquid inflow line L1 ': Discharge line
L2: Presence supply line L3: Concentrate supply line
L4: Mixed feed line L5: Feed line
L6: fuel addition line P1: exhaust pump
P2: Feed pump P3: Feed pump
V1: First valve V1 ': Wastewater supply valve
V2: second valve V3: third valve
V4: fourth valve

Claims (5)

A host consisting of Fe (III) - (NH4) 2-EDTA; And
A mixture comprising a magnesium carboxyl compound;
Wherein the chemical cleaning wastewater is used as a fuel additive for a coal boiler.
The method according to claim 1,
The magnesium carboxyl compound may be, for example,
Characterized in that the magnesium concentration is made to be 2.9 mol / L or more by dissolving 3.6 to 4.6 mol of magnesium hydroxide in an aqueous solution containing 0.5 to 1.6 mol of citric acid, 1.6 to 4.8 mol of acetic acid and 2.1 to 6.6 mol of formic acid. Fuel Additives for Coal Boiler Using.
The method according to claim 1,
The magnesium carboxyl compound may be, for example,
Characterized in that the magnesium concentration is made to be 2.9 mol / L or more by dissolving 2.5 to 3.8 mol of magnesium oxide in an aqueous solution containing 0.5 to 1.6 mol of citric acid, 1.6 to 4.8 mol of acetic acid and 2.1 to 6.6 mol of formic acid. Fuel Additives for Coal Boiler Using.
A main tank 10 in which chemical cleaning wastewater is stored;
A concentrating tank 20 for heating the chemical washing wastewater supplied from the main tank 10 using a heater 21 to produce a concentrate;
A mixing tank 30 connected to the concentrating tank 20 and supplied with the concentrate prepared in the concentrating tank 20;
A mixer tank (40) connected to the mixing tank (30) and supplying a predetermined amount of mixed agent to the mixing tank (30);
A storage tank 50 connected to the mixing tank 30 and supplied with the mixed fuel additive in the mixing tank 30 and stored; And
An injector (60) for injecting the fuel additive stored in the storage tank (50) through a fuel inlet of the boiler;
Lt; / RTI >
The concentrated liquid, which is concentrated in the concentration tank 20,
Fe (III) - (NH4) 2-EDTA,
The mixed agent stored in the mixed tank (40)
Wherein the chemical cleaning wastewater is a magnesium carboxylate compound. delete

Images