Sinter plant gas cleaning system

Patent metadata

Field	Value
Publication number	US-9120045-B2
Application number	US-201414279837-A
Country	US
Kind code	B2
Filing date	May 16, 2014
Priority date	Nov 25, 2011
Publication date	Sep 1, 2015
Grant date	Sep 1, 2015

Abstract

A sinter plant gas cleaning system includes a fabric filter device for removing dust particles from a process gas drawn from a sinter strand of a sinter plant. A duct is adapted to allow the process gas drawn from the sinter strand to pass by the fabric filter device. A measurement device measures a concentration of organic compounds of the process gas drawn from the sinter strand. A control system receives a signal from the measurement device and controls the flow of process gas through the duct.

First claim

The invention claimed is:

1. A method of controlling a sinter plant gas cleaning system having a pre-collector device and a fabric filter device for removing dust particles from a process gas drawn from a sinter strand of a sinter plant, the method comprising:
measuring a concentration of organic compounds of the process gas drawn from the sinter strand, and
passing a flow of the process gas having dust particles from the pre-collector device through at least one duct located between the pre-collector device and the fabric filter device; and
controlling, based on the measured concentration of organic compounds of the process gas, a flow of process gas by-passing the fabric filter device, wherein the controlling, based on the measured concentration of organic compounds of the process gas, the flow of process gas by-passing the fabric filter device, comprises:
determining a measured concentration of Non Methanic Volatile Organic Compounds (NMVOC) in the process gas prior to the process gas being sent to at least one of a stack and the fabric filter device;
splitting the process gas having the dust particles into a first flow and a second flow such that 50% of the process gas is forwarded through to the fabric filter device as the first flow and 50% of the process gas bypasses the fabric filter device as the second flow of process gas when a measured concentration of NMVOC in the process gas is between 60 and 100 mg of NMVOC per Nm 3 of dry gas, the second flow of the process gas being the flow of process gas by-passing the fabric filter device;
sending an entirety of the process gas having the dust particles to the fabric filter device so that 100% of the process gas is passed through the fabric filter device when the measured concentration of NMVOC in the process gas is between 0 and 60 mg of NMVOC per Nm 3 of dry gas; and
sending an entirety of the process gas having the dust particles to a stack such that the entirety of the process gas bypasses the fabric filter device when the measured concentration of NMVOC in the process gas is greater than 100 mg of NMVOC per Nm 3 of dry gas, the process gas that bypasses the fabric filter device being the flow of process gas by-passing the fabric filter device.

2. The method according to claim 1 , further comprising controlling, based on the measured concentration of organic compounds of the process gas, a supply of an additive comprising an alkaline substance to the process gas upstream of the fabric filter device.

3. The method according to claim 1 , further comprising supplying an additive to the process gas upstream of the fabric filter device in an amount which corresponds to one of 100-1,000 mg of alkaline substance per Nm 3 of dry process gas and 200-400 mg of alkaline substance per Nm 3 of dry process gas.

4. The method according to claim 1 , further comprising supplying an additive comprising an alkaline substance to the process gas upstream of the fabric filter device during at least 50% of the time that the process gas is allowed to pass through the fabric filter device.

5. The method according to claim 2 , further comprising supplying an additive comprising an alkaline substance selected from a group of alkaline substances comprising: hydrated lime, Ca(OH) 2 , limestone, CaCO 3 , sodium carbonate, Na 2 CO 3 , sodium bicarbonate, NaHCO 3 , fly ash collected from flue gases of a coal fired power boiler, fly ash collected from a biomass fired power boiler, and mixtures thereof.

6. The method according to claim 1 , wherein the controlling the flow of process gas by-passing the fabric filter device further comprises comparing the measured concentration of organic compounds of the process gas to a set point, and increasing the amount of the process gas by-passing the fabric filter device when the measured concentration of organic compounds of the process gas exceeds the set point.

7. The method according to claim 1 , further comprising comparing a measured concentration of NMVOC to a set point for NMVOC, the set point being 100 mg, or less, of NMVOC per Nm 3 dry process gas, and causing more than 50% of the process gas to by-pass the fabric filter device when the measured concentration of NMVOC exceeds the set point.

8. The method according to claim 1 , further comprising recirculating at least a portion of an amount of dust particles collected in the fabric filter device and mixing the recirculated dust particles with process gas about to enter the fabric filter device.

9. The method according to claim 1 , further comprising forwarding the process gas through the pre-collector device also when a flow of process gas by-passes the fabric filter device.

10. The method according to claim 1 , comprising:
splitting the flow of the process gas having the dust particles into a first flow and a second flow;
passing the first flow through a reactor to supply an alkaline substance to that portion of the process gas prior to that portion being passed to the fabric filter device;
passing the first flow through the fabric filter device after the first flow passes through the reactor to collect the dust particles from the process gas of the first flow;
passing the second flow such that the second flow bypasses the fabric filter device the second flow of the process gas being the flow of the process gas by-passing the fabric filter device;
mixing the second flow with the process gas of the first flow after the first flow has passed through the fabric filter device; and
passing the mixed first and second flows to a stack.

11. The method of claim 1 , wherein the determining of the measured concentration of NMVOC in the process gas prior to the process gas being sent to at least one of a stack and the fabric filter device comprises:
determining a total concentration of organic compounds in the process gas;
determining a concentration of methane in the process gas; and
subtracting the concentration of methane from the total concentration of organic compounds to determine the concentration of NMVOC in the process gas.

12. The method of claim 1 , wherein the sinter plant gas cleaning system comprises:
a by-pass duct adapted to allow at least a portion of the process gas drawn from the sinter strand to by-pass the fabric filter device,
a measurement device for measuring a concentration of organic compounds of the process gas drawn from the sinter strand, and
a control system adapted to receive a signal from the measurement device and to control, in view of the signal received, the flow of process gas passing through the by-pass duct.

13. The method of claim 12 , wherein the gas cleaning system comprises an additive supply system for supplying an additive comprising an alkaline substance to the process gas upstream of the fabric filter device.

14. The method of claim 12 wherein the control system is adapted to receive a signal from the measurement device and to control, in view of the signal received, an amount of additive comprising an alkaline substance supplied to the process gas by an additive supply system.

15. The method of claim 12 , wherein the pre-collector device is fluidly connected in series with the by-pass duct such that dust particles are removed from the process gas also when a flow of process gas by-passes the fabric filter device.

16. The method of claim 15 , wherein the pre-collector device comprises at least one of: an electrostatic precipitator and a multi-cyclone unit, and wherein the pre-collector device is arranged upstream, as seen with respect to a transport direction of the process gas, of the fabric filter device.

Assignees

• Alstom Technology Ltd

Inventors

• Wieslander Peter
• Loren Lena

Classifications

• B01D53/72

  Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons · CPC title

• B01D2257/2064

  Chlorine · CPC title

• B01D53/83

  with moving reactants · CPC title

• B01D2257/7022

  Aliphatic hydrocarbons · CPC title

• B01D2257/708

  Volatile organic compounds V.O.C.'s · CPC title