Lignite drying with a heat recovery circuit

Patent metadata

Field	Value
Publication number	US-9944874-B2
Application number	US-201615162987-A
Country	US
Kind code	B2
Filing date	May 24, 2016
Priority date	May 26, 2015
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

The invention relates to a lignite fired steam power plant comprising a water/steam power cycle, a dryer system for drying lignite coal and a heat recovery system for recovering thermal energy from the dryer system. The heat recovery system vaporises condensate against a vapour line of the dryer steam and then compresses the vaporised condensate for use to preheat either or both combustion air or condensate of the water/steam power cycle.

First claim

The invention claimed is:

1. A lignite fired steam power plant comprising:
a water/steam power cycle having:
a pressure series of steam turbines;
a condenser at a low pressure end of pressure series of steam turbines configured and arrange to condense steam exhausted from the low pressure end of the pressure series of steam turbines;
a first condensate line connected to the condenser; and
a low pressure condensate preheat system, in the first condensate line, adapted to preheat condensate from the condenser;

a dryer system for drying lignite coal, the dryer system having:
a dryer; and
a vapour outlet line for removing vapour from the dryer,

a heat recovery system for recovery of thermal energy from the vapour outlet line, the heat recovery system comprising:
a second condensate line, fluidly spanning between the condenser and the first condensate line so as to at least partially bypass the low pressure condensate preheat system;
a third condensate line extending from the condenser to the low pressure condensate preheat system so as to bypass at least a portion of the low pressure condensate preheat system and at least a portion of the second condensate line;
a condensate evaporator fluidly connected to the vapour outlet line and the third condensate line so as to enable evaporation of a condensate in the third condensate line against condensing vapour in the vapour outlet line;
a first compressor, in the third condensate line downstream of the condensate evaporator, adapted to compress the evaporated condensate from the condensate evaporator; and
a first heater connected to and downstream of the first compressor for desuperheating and condensing vapour from the first compressor.

2. The lignite fired steam power plant of claim 1 , wherein the second condensate line additionally passes through the first heater so as to enable condensation of the evaporated condensate of the third condensate line against a condensate of the second condensate line.

3. The lignite fired steam power plant of claim 1 , further comprising, in the second condensate line, a second heater that is connected to a first branch of the vapour outlet line branching from the vapour outlet line upstream of the condensate evaporator, so as to enable condensation of the vapour of the first branch against a condensate in the second condensate line.

4. The lignite fired steam power plant of claim 3 , wherein the second heater is located in the second condensate line upstream of the first heater.

5. The lignite fired steam power plant of claim 3 , further comprising:
a third heater in the second condensate line, downstream of the first heater; and
a second compressor, connected to the third condensate fluidly between the first compressor and the first heater, and further connected to the third heater, so as to enable heating of the condensate from the second condensate line with an exhaust from the second compressor.

6. The lignite fired steam power plant of claim 3 , further comprising:
a second branch that branches from the vapour outlet line upstream of the condensate evaporator; and
a first combustion air heat exchanger in the second branch, so as to enable heating of a combustion air in the first combustion air heat exchanger with a vapour of the second branch.

7. The lignite fired steam power plant of claim 3 , further comprising a first combustion air heat exchanger connected to the second heater so as to enable heating of a combustion air with a fluid of the first branch exiting the second heater.

8. The lignite fired steam power plant of claim 6 , comprising a second combustion air heat exchanger, connected to and downstream of the first compressor and downstream of the first combustion air heat exchanger, for desuperheating and condensing vapour from the first compressor and enabling further heating of the combustion air of the lignite steam power plant.

9. The lignite fired steam power plant of claim 1 wherein the first heater is configured and arranged to heat a combustion air.

10. The lignite fired steam power plant of claim 1 wherein the third condensate line extends to the low pressure condensate preheat system by joining the second condensate line.

Assignees

• Alstom Technology Ltd
• General Electric Technology Gmbh

Inventors

• Edel Thomas
• Geiger Frederic
• Pourchot Thierry
• Wantz Didier

Classifications

• F26B3/08 Primary

  so as to loosen them, e.g. to form a fluidised bed {("fluidised-bed" technique in general B01J8/24; centrifugal fluidised beds F26B7/007)} · CPC title

• F01K5/00

  Plants characterised by use of means for storing steam in an alkali to increase steam pressure, e.g. of Honigmann or Koenemann type · CPC title

• F01K7/16

  the engines being only of turbine type (the engines using steam of critical or overcritical pressure F01K7/32; the engines being of extraction or non-condensing type F01K7/34) · CPC title

• C10L5/04 Primary

  Raw material {of mineral origin} to be used; Pretreatment thereof {(pretreatment of fuels of non-mineral origin C10L5/40)} · CPC title

• F26B23/10

  using tubes or passages containing heated fluids {, e.g. acting as radiative elements; Closed-loop systems (for combustion gases F26B3/305)} · CPC title