KR100375331B1 - Regenerable manganese-based sorbents for removal of hydrogen sulfide and method for preparing the same - Google Patents

Abstract

The present invention relates to a desulfurization agent for removing hydrogen sulfide at a high temperature and a method for preparing the same.

Desulfurization agent for removing hydrogen sulfide of the present invention comprises 75% by weight of MnCO _3, 20% by weight of TiO ₂ and 5% by weight of bentonite, mixing each sample in a powder state; Drying until constant weight; Firing; Curing; And by pulverizing and sieving the cured desulfurization agent, the desulfurization agent of the present invention has excellent hydrogen sulfide removal effect at high temperature.

Description

Regenerable manganese-based sorbents for removal of hydrogen sulfide and method for preparing the same}

The present invention relates to an efficient desulfurization agent capable of removing hydrogen sulfide and regeneration and a method for producing the same.

Domestic electricity production accounts for 36% of nuclear power generation and 28% of thermal power generation as of 1996, and coal consumption for thermal power generation is expected to increase to about 36% in early 2000.

Although coal has abundant reserves worldwide and favorable conditions in terms of supply stability and economic feasibility, it is difficult to continuously increase the utilization of the coal direct combustion method. The development of rational coal utilization technology is urgently needed.

The Integrated Gasification Combined Cycle (IGCC) technology is one of the best alternatives to pulverized coal-fired power generation in terms of environmental friendliness, fuel security and thermal efficiency. The business continues steadily, reaching the deepening stage.

Coal gasification combined cycle powers coal with oxygen in a gasifier of high temperature and high pressure (1200 ~ 1500 ℃, 25kg / ㎠) and gasifies it, and removes dust and sulfur components from dust collector and desulfurization unit. Used as. The thermal efficiency of the system has been evaluated to be more than 15% higher than the thermal efficiency by 45-50% (30-33%) of a conventional pulverized coal-fired power generation, in particular CO ₂ emissions regulations are increasingly enhanced CO ₂ emission is suppressed by more than 10% It is also very preferable from the viewpoint.

Fuel gases contaminated with ash, sulfur, nitrogen, alkali metals and various trace contaminants in coal are deposited or corroded in gas turbines, which shortens the durability of the system and causes environmental problems. Should be removed.

In the United States, the METC (Morgantown Energy Technology Center) under the Department of Energy (DOE) has been involved in research and development of high-temperature dry desulphurizers and processes for about 20 years. have.

The metal oxide desulfurization agents studied so far are Zn, Fe, Cu, Ca, Mg, V, Mn, Ni, Co, Sn, Pb, Bi, Cd, Mo, W, Cr and others. It has both advantages and disadvantages.

According to various experiments, Zn, Fe, Cu, Mn, Ce, etc. are the primary active ingredients that can reduce the concentration of H ₂ S in coal gas below 20ppmv, and additives include Cu, Fe, Mn, Cr, Ce, Co, Mo, Ni, and the like, Al ₂ O _3, SiO _2, TiO _2, ZrO ₂ and the like has been reported that can be used (Ryu Cheong-gal, Chemical Industry and Technology, 1998).

Among the desulfurization agents developed so far, the commercialization stage is a mixed zinc desulfurization agent, and in recent years, much attention has been focused on the preparation and experimentation of manganese desulfurization agents in an attempt to overcome the disadvantages of the zinc desulfurization agent.

Westmoreland et al. (Environmental Science Technology, 22 (5), 1977) conducted a kinetic study to predict the stability of manganese oxides and desulfurization at temperatures above 1000 ° C. From these kinetic considerations, the relative magnitudes of the initial reaction rates between H ₂ S and MnO, CaO, ZnO and V ₂ O ₃ at 300 to 800 ° C were MnO>CaO>ZnO> V ₂ O ₃ . Therefore, in this study, the researchers concluded that MnO was most effective for high temperature desulfurization processes.

Turkdogan and Olsson et al. (Proceedings of the Third International Iron and Steel Congress ASM, pp. 277-288, 1979) have tested the availability of manganese oxides at high temperature desulfurization and mix Mn and alumina in a 3: 1 weight ratio. It has been found that sulfur can be removed from the H ₂ -H ₂ S gas mixture at 800 ° C. and regenerated with air.

Hepworth et al. (Energy Fuels, 7 (6), 1993) reported that, from a thermodynamic perspective, to evaluate the behavior of single or complex metal desulfurization agents to remove sulfur from hot fuel gases, manganese, iron, nickel, magnesium, copper, sodium, Studies on linked metals have shown that manganese oxide is the best metal with low reducibility and can be used over a wide temperature range.

The first challenge to commercialize high-temperature dry desulfurization technology, which is the core technology of IGCC power generation, is to develop a renewable desulfurization agent with good physical and chemical properties.

Manganese-based desulfurization agents can be operated at high temperatures because they have a high reduction resistance to elemental manganese and a melting temperature of 1,232 ℃ even when applied to all fuel gases generated in the actual gasifier.

In addition, there is an advantage that the reaction rate is much faster than the zinc-based desulfurization agent.

Accordingly, the present invention provides a manganese-based desulfurization agent capable of adsorbing and removing hydrogen sulfide generated at a coal gasification combined cycle at high temperature, and a method of manufacturing the same.

Desulfurization agent composition of the present invention for achieving the above object is composed of 75% by weight of MnCO _3, 20% by weight of TiO ₂ and 5% by weight of bentonite, the desulfurizing agent manufacturing method of the present invention comprises the steps of mixing each sample in the powder state; Drying until constant weight; Firing; Curing; And pulverizing and sieving the cured desulfurization agent.

1 is a process diagram schematically showing a desulfurization agent manufacturing process of the present invention

2 is a graph showing a breakthrough curve of hydrogen sulfide removal using the composition of the present invention.

Looking at the present invention in more detail as follows.

Mechanisms of hydrogen sulfide removal by manganese oxides and iron oxides that are reactive with hydrogen sulfide can be divided into reduction and sulfidation stages. First, M _a O _b → M _c O _d (where b / a> d / c, M is manganese or iron) and M _c O _d reacts with H ₂ S to sulfide into MS.

In addition, since MnO has a very small equilibrium constant of the reduction reaction by hydrogen, reduction to manganese rarely occurs, whereas Fe ₂ O ₃ has a high reducibility and is easily reduced by hydrogen or carbon monoxide.

Most regeneration of metal oxide desulfurization agents uses air / steam mixture gas including steam as air or oxygen-deficient air and diluent, and physical durability and reactivity of desulfurization agent by adjusting regeneration conditions such as temperature, oxygen concentration and regeneration gas characteristics. It is necessary to maintain.

Excessive temperature rise in regeneration leads to sintering of the desulfurization agent, which leads to loss of porosity and decrease in reactivity. Regeneration at low temperature leads to the formation of sulphate, which is difficult to decompose once produced and acts as a diffusion barrier for oxygen. Not desirable

Therefore, it is important to find the optimal operating conditions to minimize sulfate formation and sintering effect by preventing hot spots through temperature control and oxygen concentration control in regenerative reaction.

The reaction mechanisms for reduction, sulfidation and regeneration of manganese and iron are as follows.

Scheme 1

(MnO _2, Mn ₂ O, Mn ₃ O ₄ ) + H ₂ (or CO) → MnO + H ₂ O Scheme 1 shows a process in which manganese oxide is reduced by reacting with a reducing gas.

Scheme 2

MnO + H ₂ S → MnS + H ₂ O Scheme 2 shows a process in which manganese oxide is reacted with hydrogen sulfide after reduction to remove hydrogen sulfide.

Scheme 3

2MnS + 7 / 2O ₂ → Mn ₂ O ₃ + 2SO ₂ Scheme 3 shows a process in which manganese oxide is regenerated by oxygen after sulfidation.

Production Example

Looking at the desulfurizer manufacturing process of Figure 1, the material used to prepare the manganese-based desulfurization agent of the present invention is MnCO ₃ 75% by weight, TiO ₂ 20% by weight, bentonite 5% by weight.

MT (MnCO ₃ , TiO ₂ ) desulfurization agent of the manganese-based primary active ingredient was prepared using the above reagent, and the MT desulfurization agent name is named for convenience of the applicant.

The MT desulfurization agent used TiO ₂ as a support, and bentonite was used as a binder for the desulfurization agent. The desulfurization agent manufacturing method of the present invention will be described. 75 wt% MnCO _{3 in} powder form, 20 wt% TiO ₂ , and 5 wt% Bentonite % Samples were mixed according to each weight ratio, deionized water was added to make a slurry, dried until it became a constant in a drying oven (110 ℃), and then calcined at 400 ℃ for 5 hours to manganese carbonate (manganese). carbonate) was decomposed.

After firing, the mixture was transferred to a high temperature furnace preheated to 400 ° C., heated to a curing temperature, and cured for 2 hours under an air atmosphere (about 1 L / min).

The final product was pulverized and sieved by particle diameter, 20 / 40mesh was used for sulfidation and regeneration experiments, and fine particles below 60mesh were used for physical property analysis of the desulfurization agent.

Example

Manganese-based desulfurizing agent in the low temperature of 550, 650 ℃ more of 400~800 ℃ range shown to be effective in removing H ₂ S examined the temperature characteristics of the specific sulfide MT.

The sulfidation results according to temperature at 0.5% H ₂ S-10% H ₂ -bal N _{2 and} flow rate 190ml / min are shown in FIG. 2.

Normalized sulfidation time t / t * is defined as the ratio of the actual time t to the theoretical time t * required for the complete sulphation of the solvent used in each experiment to form MnS. T / t * thus corresponds to the desulphurization partial conversion.

In case of MT, partial conversion was 0.89 and 1.1 at 550 ℃ and 650 ℃, respectively, and the equilibrium concentration of MT was 20 ~ 65ppmV, showing excellent thermodynamic characteristics.

From the results of FIG. 2, the MT desulfurization agent was able to observe a very good desulfurization ability in the middle temperature range.

The present invention relates to a manganese-based desulfurization agent that adsorbs and removes hydrogen sulfide at a high temperature, and a method of manufacturing the same. The present invention has a high reduction resistance as elemental manganese even when applied to all fuel gases, and can operate at high temperatures. There is this.

Claims (6)

MT desulfurization agent which is a manganese desulfurization agent reacting with hydrogen sulfide at 550-800 ° C., desulfurization agent for removing hydrogen sulfide, characterized in that consisting of 75% by weight of MnCO ₃ + 20% by weight of TiO ₂ + 5% by weight of bentonite. A desulfurization agent based on MnCO ₃ , 75% by weight, 20% by weight of TiO ₂ , and 5% by weight of bentonite; Drying the sample at 110 ° C. until it reaches a constant weight; Firing the dried sample at 400 ° C .; A curing step of curing the fired sample at 1100 ° C .; Method for producing a desulfurization agent for removing hydrogen sulfide, characterized in that it comprises a pulverizing step of pulverizing and sieving the cured desulfurization agent. delete delete delete delete