Cleaning system and method for reduction of SOx in exhaust gases

Patent metadata

Field	Value
Publication number	US-9982582-B2
Application number	US-201414442747-A
Country	US
Kind code	B2
Filing date	Mar 4, 2014
Priority date	Mar 8, 2013
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A cleaning system for reducing SOx and particulate matter in exhaust gases from a marine combustion engine, burner or boiler. The cleaning system comprises first and second scrubber process loops having first and second scrubber, respectively, and first and second water circulation tanks, respectively. Water from the first tank is evaporated to water vapor inside the first scrubber by contact with the exhaust gases, whereby the water vapor and the exhaust gases form humid exhaust gases. The humid exhaust gases are transferred to the second scrubber, wherein water from the second tank condensates the water vapor in the humid exhaust gases. A reflux of water from the second scrubber process loop to the first scrubber process loop is provided. At least 60% and more preferred at least 90% of a total amount of alkaline agent supplied to the cleaning system is supplied to the second scrubber process loop.

First claim

The invention claimed is:

1. Cleaning system for the reduction of SOx and particulate matter in exhaust gases from a marine combustion engine, burner or boiler, the cleaning system comprising:
a first scrubber process loop comprising a first scrubber and a first water circulation tank, wherein water from the first water circulation tank is arranged to circulate in the first scrubber process loop, the first scrubber being arranged to receive exhaust gases from the combustion engine, burner or boiler and water from the first water circulation tank, which water, at least partly, is arranged to be evaporated to water vapor inside the first scrubber by contact with the exhaust gases, whereby the water vapor and the exhaust gases form humid exhaust gases;
a second scrubber process loop comprising a second scrubber and a second water circulation tank, wherein water from the second water circulation tank is arranged to circulate in the second scrubber process loop,
a communication between the first and the second scrubber allowing transfer of the humid exhaust gases from the first scrubber to the second scrubber; the second scrubber being arranged to receive water from the second circulation tank, which water is arranged to condensate, inside the second scrubber, the water vapor in the humid exhaust gases at least partly; and
a communication between the first and the second scrubber process loop allowing a reflux of water from the second scrubber process loop to the first scrubber process loop,
the cleaning system further comprising an arrangement for supply of an alkaline agent to at least the second scrubber process loop, wherein at least 60% of the total amount of the alkaline agent supplied to the cleaning system is supplied to the second scrubber process loop.

2. The cleaning system according to claim 1 , wherein the second scrubber process loop comprises a first heat exchanger adapted to cool the water being arranged to circulate in the second scrubber process loop.

3. The cleaning system according to claim 1 , adapted to maintain a temperature of the water arranged to be received by the second scrubber in the range of 0-35° C.

4. The cleaning system according to claim 1 , adapted to maintain a temperature of the water arranged to be received by the first scrubber in the range of 40-70° C.

5. The cleaning system according to claim 1 , adapted to adjust the supply of the alkaline agent to the second scrubber process loop such that a pH value of the water arranged to be received by the second scrubber is in the range of 6-10.

6. The cleaning system according to claim 1 , adapted to maintain a pH value of the water arranged to be received by the first scrubber in the range of 2-8.

7. The cleaning system according to claim 1 , further comprising a first separator unit communicating with the first scrubber process loop.

8. The cleaning system according to claim 7 , further comprising a water cleaning arrangement adapted to be supplied with remnant water from the first separator unit, wherein the water cleaning arrangement comprises a second heat exchanger adapted to cool the remnant water in order for salts contained therein to precipitate, and a second separator unit adapted to separate the precipitated salts from the cooled remnant water.

9. Method of reducing SOx and particulate matter in exhaust gases from a marine combustion engine, burner or boiler by using a cleaning system, the cleaning system comprising:
a first scrubber process loop comprising a first scrubber and a first water circulation tank;
a second scrubber process loop comprising a second scrubber and a second water circulation tank;
a communication between the first and the second scrubber;
a communication between the first and the second scrubber process loop; and
an arrangement for supply of an alkaline agent to at least the second scrubber process loop; the method comprising:
circulating water from the first water circulation tank in the first scrubber process loop,
circulating water from the second water circulation tank in the second scrubber process loop,
supplying at least 60% of the total amount of the alkaline agent supplied to the cleaning system to the second scrubber process loop,
receiving exhaust gases from the combustion engine, burner or boiler, and water from the first water circulation tank, in the first scrubber, which water, at least partly, is evaporated to water vapor inside the first scrubber by contact with the exhaust gases, whereby the water vapor and the exhaust gases form humid exhaust gases,
transferring the humid exhaust gases from the first scrubber to the second scrubber,
receiving water from the second circulation tank in the second scrubber, which water condensates, inside the second scrubber, the water vapor in the humid exhaust gases at least partly, whereby SOx contained in the exhaust gases oxidizes into sulphates; and
providing a reflux of water from the second scrubber process loop to the first scrubber process loop.

10. The method of claim 9 , comprising adjusting the supply of the alkaline agent to the second scrubber process loop such that a pH value of the water received in the second scrubber is in the range of 6-10.

11. The method of claim 9 , comprising maintaining a pH value of the water arranged to be received in the first scrubber in the range of 2-8.

12. The method of claim 9 , further comprising cooling the water arranged to be received in the second scrubber to a temperature in the range of 0-35° C.

13. The method of claim 9 , further comprising maintaining a temperature of the water arranged to be received in the first scrubber in the range of 40-70° C.

14. Use of a cleaning system comprising operating the cleaning system according to claim 1 while the cleaning system is onboard a ship for the purpose of reduction of SO x and particulate matter in exhaust gases from a marine combustion engine, burner or boiler located onboard the ship.

15. The cleaning system according to claim 1 , wherein at least 90% of the total amount of the alkaline agent supplied to the cleaning system is supplied to the second scrubber process loop.

16. The cleaning system according to claim 1 , wherein the cleaning system is adapted to adjust the supply of the alkaline agent to the second scrubber process loop such that the pH value of the water arranged to be received by the second scrubber is in the range of 7-8.

17. The cleaning system according to claim 1 , wherein the cleaning system is adapted to maintain a pH value of the water arranged to be received by the first scrubber in the range of 2-4.

18. The method of claim 9 , wherein the supplying of at least 60% of the total amount of the alkaline agent supplied to the cleaning system to the second scrubber process loop comprises supplying at least 90% of the total amount of the alkaline agent supplied to the cleaning system to the second scrubber process loop.

19. The method of claim 9 , wherein the adjusting of the supply of the alkaline agent to the second scrubber process loop comprises adjusting the supply of the alkaline agent to the second scrubber process loop such that the pH value of the water received in the second scrubber is in the range of 7-8.

20. The method of claim 9 , wherein the maintaining of the pH value of the water arranged to be received in the first scrubber comprises maintaining the pH value of the water arranged to be received in the first scrubber in the range of 2-4.

Assignees

• Alfa Laval Corp Ab

Inventors

• Molgaard Soren
• Hansen Jens Peter

Classifications

• F01N13/0093

  the purifying devices are of the same type · CPC title

• F01N3/04 Primary

  using liquids · CPC title

• B01D53/1406

  Multiple stage absorption · CPC title

• B01D2257/302

  Sulfur oxides · CPC title

• F01N3/085 Primary

  Sulfur or sulfur oxides · CPC title