# US 10,369,519 B2 · Method for removing mercury from flue gases of incineration plants

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- Number: US 10,369,519 B2
- Document ID: US10369519B2
- Status: Granted
- Kind: B2
- Application number: 15/737,926
- Filed: 2016-05-30
- Published: 2018-06-21
- Granted: 2019-08-06
- Earliest claimed: 2015-06-19
- Assignees: Rwe Power Aktiengesellschaft
- Applicants: RWE Power Aktiengesellschaft
- Inventors: Peter Moser; Knut Stahl
- Web page: https://patentgrep.com/patent/US10369519B2

## CPC

- B01D 53/80: Semi-solid phase processes, i.e. by using slurries
- B01D 53/50: Sulfur oxides (B01D53/60 takes precedence)
- B01D 53/64: Heavy metals or compounds thereof, e.g. mercury
- B01J 20/20: comprising free carbon; comprising carbon obtained by carbonising processes
- B01J 20/28004: {Sorbent size or size distribution, e.g. particle size}
- B01J 20/3021: {Milling, crushing or grinding}
- B01J 20/3416: {of sorbents or filter aids comprising free carbon, e.g. activated carbon}
- B01D 2253/102: Carbon
- B01D 2257/302: Sulfur oxides
- B01D 2257/602: Mercury or mercury compounds
- B01D 2258/0283: Flue gases
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

The invention relates to a process for removing mercury from flue gases from combustion plants, wherein the process comprises providing an adsorbent based on carbon, producing an aqueous suspension comprising the adsorbent, introducing the suspension into the flue gas stream from the combustion plants into the dry gas phase of the flue gas which is undersaturated with water vapor and loading the adsorbent with mercury over a predetermined reaction path, keeping the mercury-laden adsorbent out of the flue gas stream and landfilling or regenerating the mercury-laden adsorbent.

## Claims

### Claim 1

A process for removing mercury from flue gas from a combustion plant, comprising:
a) providing an adsorbent selected from a group consisting of activated carbon, activated coke, molecular sieves, carbon molecular sieves and mixtures of the abovementioned adsorbents;
b) producing an aqueous suspension comprising the adsorbent;
c) introducing the suspension into a flue gas stream of the combustion plant of the flue gas and loading the adsorbent with mercury over a predetermined reaction path;
d) keeping the adsorbent loaded with mercury out of the flue gas stream by one or more removal methods selected from a group consisting of a dry offgas purification and a wet offgas purification; and
e) land filling or regenerating the adsorbent loaded with mercury,
wherein the process comprises a wet flue gas desulfurization, wherein a carbon-enriched adsorbent which is based on brown coal and has been activated in an absence of oxygen is used as the adsorbent according to process step a), in that the introduction of the suspension as per process step c) into a dry, water vapor-undersaturated gas phase of the flue gas is effected upstream, in a flow direction of the flue gas, of the flue gas desulfurization, at a temperature of the flue gas in a range from 100° C. to 220° C.

### Claim 2 (depends on 1)

The process as claimed in claim 1, wherein the adsorbent is wet milled for producing the suspension in process step b).

### Claim 3 (depends on 2)

The process as claimed in claim 2, wherein the milling of the adsorbent is carried out using a ball mill.

### Claim 4 (depends on 3)

The process as claimed in claim 3, wherein the ball mill is a stirred ball mill.

### Claim 5 (depends on 2)

The process as claimed in claim 2, wherein the adsorbent is wet milled to an average particle diameter in a range from 10 to 20 μm.

### Claim 6 (depends on 1)

The process as claimed in claim 1, wherein the introduction of the suspension in process step c) is effected by injection into a flue gas channel of the combustion plant, using spray nozzles distributed over a cross section of the flue gas channel.

### Claim 7 (depends on 6)

The process as claimed in claim 6, wherein single-fluid nozzles are employed as spray nozzles.

### Claim 8 (depends on 1)

The process as claimed in claim 1, wherein the suspension comprises from 3% to 30% by weight of solid.

### Claim 9 (depends on 8)

The process as claimed in claim 8, wherein the suspension comprises from 5% to 15% by weight of solid.

### Claim 10 (depends on 1)

The process as claimed in claim 1, wherein the process comprises dry keeping-out of the mercury-laden adsorbent as per process step d) using at least one filter device selected from a group consisting of electrofilters, centrifugal precipitators, woven fabric filters, tube filters, filter cloths, bag filters and candle filters.

### Claim 11 (depends on 1)

The process as claimed in claim 1, wherein halides selected from a group consisting of iodides, chlorides, sodium bromide, calcium bromide and hydrogen bromide are added to the suspension before process step c).

### Claim 12 (depends on 1)

The process as claimed in claim 1, as process for removing mercury from flue gas from coal-fired power stations having a wet flue gas desulfurization plant.