Use of flue gas and its filtration

Use of flue gas and its filtration in biomass heating plant

Basic investor´s requirement: reduce the solid pollutant emissions below the legal limit in Czech Republic (30 mg/m³).

TARPO company has designed the technology that, in its first part, recuperates a maximum possible heat output from the flue gas in boiler into their return water, and in the second pars uses the principle of wet scrubbing to clean the flue gas to the newly required emission limit.

The result is savings a fuel and operating costs of about 17 % for the biomass heating plant.

ADVANTAGES OF PROPOSED SOLUTION

• compactness of solution = one device ensures both - flue gas filtration and maximum possible use of flue gas to save fuel
• it is not affected and discrupted transport system of fuel into the boilers
• power consumption of the whole new device has only 30 % increase in costs than before
• gradual implementation in stages that will not affect the operation of heating plant
• unattended, reliable operation without any significant spare parts.

TECHNOLOGY DESCRIPTION

Collecting flue gas from individual boilers is built for the box with recuperation and wet scrubbing technology. After the flue gas passes through the heat exchangers, the flue gas passes through two stages of wet scrubbing, where amount of solids is reduced to a level 10-15 mg/m³ and continued to a new stainless steel chimney.

The recuperative heat exchangers will be brought the heat pipes, where is the coldest water around the water heating circuit. Heat recuperation from the flue gas/water exchangers to the "return pipe" will allow the most efficient use of flue gas heat to preheat the water flowing through the collector to the boiler inlet. In this way is possible to recover 12 % of heat and save the same amount of fuel.

Another recuperator in the box technology will provide heat for the combustion air preheating circuit to 60-70 % and thus a further heat and fuel sawing of 4-5 %. The total fuel saving is therefore 16-17 %.

The water scrubber contains the circulating pumps of wash water, the water distribution, the collecting tank, the sludge separator and the sewerage drainege for excess wash water and condensate. The amount of suspended solids discharges in the wastewater will be a maximum of 2 t/year in the annual balance, which complies with the sewerage system.

RANGE OF TECHNOLOGY

• flue gas pipeline with shut-off flaps
• chamber with heat recovery exchangers including rinsing nozzles
• wet scrubber chamber including rinsing nozzles
• auxiliary steel construction
• steel chimney including anchoring
• hot-water circuits including control and shut-off valves
• air-conditioning distributions of combustion air
• water circuits of wet scrubbing including pumps and accessories
• wet scrubber tank and sludge separator
• sewage pipes
• thermal insulation.

   Conceptual design of technology for reduce the solid pollutant emissions