BOX 19: Case Sudies of Projects Supported by the Danish Environmental Support Fund

The Dolna Odra power plant complex in Poland comprises of eight 200 MW coal-fired units. Initially two electronic precipitators and two additional precipitators were financed followed by the implementation of a flue gas monitoring and computer control system to minimize the energy consumption of the four-filter systems, and the installation of low NOx burners were also supported, resulting in annual reductions of 35 kt of particulates and decreased heavy metal pollution. The resulting costs of the reduction are estimated to be around USD 280 per ton of emissions. Coke oven desulfurization also took place in four plants in Ukraine. Coke oven gas is captured and converted into sulfuric acid resulting in an annual reduction of 117 kt of SO2 emissions. The cost-effectiveness is around 180-280 USD per ton.

Flue gas desulfurization has been introduced in Slovenia, Poland, the Czech Republic (see Box 20), and Hungary, and these experiences could be benefitted from for projects in Bulgaria, Romania and other countries. In Bulgaria, three desulfurization systems are currently being implemented two of them in the metallurgical sector (in Plovdiv and Eliseina), and one in the Maritza-East 2 thermal power plant.

BOX 20: Modernization and Desulfurization of the CEZ Coal Plants

In order to achieve the production of electricity without detrimental effect to the environment (a stated goal of the CEZ power generator industry), the first step was to ensure compliance with the requirements of Czech environmental legislation. Existing legislation establishes emission limits for solid pollutants, sulfur dioxide, nitrogen oxides and carbon oxides and offers a final deadline for compliance with these emission limits of December 31, 1998. Among the goals of the environment program were: The desulfurization of 5,930 MW of capacity throughout its 32 fossil fuel plant units by means of flue gas limestone washing (5,710 MW through wet limestone washing, and 220 MW through semi-dry washing), To construct seven fluidized bed boilers in one of the power plants, To increase the efficiency of the fly ash separators, To decrease NOx and CO emissions. The decommission the oldest generation facilities. Through these measures, a total capacity of 2,020 MW will be gradually phased out. Before CEZ's modernization and desulfurization program was initiated, the overall capacity for electricity generation was 8,447 MW. Between 1994 and 1995, desulfurization equipment was successfully installed at the Pocerady power plant (2x200 MW) and the Prunerov power plant (4x110 MW). The equipment, based on wet limestone washing methods, operates with a minimum efficiency of 92 percent. The first fluidized-bed boiler in the Czech Republic commenced a test run at the Tisova power plant in 1995. Its output is 350 t/steam/hour. The replacement of electric fly ash separators was completed at Ledvice, Chvaletice, Melnik, Pocerady and Prunerov power plants. New filters were fitted to the fluidized boilers in the Tisova power plant and to the equipment in the Nachod and Dvur Kralove nad Labem plants. A total capacity of 1,115 MW in 12 power plants has been already phased out. The overall installed capacity of Czech coal plants as of May 30, 1997 was 7,367 MW with 50 percent of these already supplied with emission control installations. 3,510 MW in Northern Bohemia are now desulfurized and fluidized-bed combustion technology is applied to 222 MW units. According to existing plans, an additional 1,300 MW will have been supplied with desulfurization units by the end of 1997. Guaranteeing the further installation of FGD equipment, the country's leading manufacturer has just signed contracts for the entire desulfurization program.

FGD units are also expected to have been installed in Poland, some 100 by 1999. Poland has also been chosen for the installation of a demonstration pilot project for desulfurization by electron beam processing. The total capital investment required for the project amounts to USD 19.95 million. Part of this amount will be provided by the Government of Poland (USD 11.69 million), while the remainder will be provided by the Japanese International Cooperation Agency, the Japanese Stabilization Fund for Poland (USD 5.01 million), and by the International Atomic Energy Agency (USD 2.25 million in the form of equipment, experts and training).

The economics of the process has been studied and shows that the system will be available for around USD 200/kW. Thus, the electron beam process is competitive with existing SO₂ removal systems with no need for additional selective catalytic reduction (SCR) removal systems for NO_x. The Polish pilot-project shows that costs are reduced by 20 percent compared with conventional installations. The system has been proven efficient for fuels with high-sulfur content which is important to all the SILAQ countries.

These examples show that when choosing an emission control installation, many criteria have to be considered in the SILAQ countries. Thus, while FGD is less expensive and more widely used, it requires large quantities of lime resources with all the associated problems related to its extraction, processing, transportation. Gypsum by-products must also be considered along with the auxiliary energy uses in the process.

Box 21 gives information on those successful measures undertaken by VEAG to reduce dust emissions from old power plants in Germany.

BOX 21: Dust Emissions Reduction from Old Power Plants in Germany

VEAG (Vereigte Enegiewerke AG) was established in 1990 to supply power to the former German Democratic Republic (GDR), and inherited the two GDR lignite-fired power plants and interconnecting networks. The electrostatic precipitators installed in the old plants were characterized by a low separation rate and a poor state of repair. This resulted in low efficiency. As a result, an emergency program was initiated in 1990 aimed at rapidly and efficiently reducing dust emissions from those plants. The reasons behind the inadequate performance of the ash-removal unit and dust separators were analyzed and remedial actions were planned. Attention was given to measures that could be carried out by the repair personnel at the site. This essentially helped to cut costs. The most important steps included: Improving/balancing the flue-gas flow in the electrostatic precipitator; Repairing the perforated plates, and the use of new materials; Repairing the spraying and precipitation systems; Restructuring the rapping gear in order to improve efficiency and operating safety; Sealing the jacket of the electrostatic precipitator; Modernizing the control unit of the rapping gear, etc. The end result was that the emissions were lower than the established standards set for the dust burden of cleaned gas, despite the fact that the equipment had been in operation for twenty years. VEAG is ready to share its experience in upgrading electrostatic precipitators and ash removal installations to all interested parties and to assist power plant operators in implementing such programs. Cooperating closely with the supply industry, VEAG developed the concept for an 800 MW unit. This type of unit was established at Schwarze Pumpe for the first time, making the new power plant the most advanced, efficient and environmentally compatible lignite-fired power plant in the world with an energy efficiency rate of 40.6 percent and specific CO2 emissions less than 1.0 kg CO2/kWhnet. The power plant operates from state-of-the-art pollution control equipment. The design of the electrostatic precipitators ensure that the dust burden of cleaned gas does not exceed 50 mg/m3 n, dry, 6 percent O2. Under normal operating conditions, values of between 5 and 15 mg/m3 have been obtained. The actual particulate emissions are as low as 1-3 mg/m3, since a second stage of dust precipitation takes place in the wet flue gas desulfurization (FGD) unit. Wet FGD is based on a two circuit process, using limestone as a sorbent. With 98 percent or 99 percent of the sulfur removed under operating conditions, the design separation rate of 95 percent is clearly surpassed. The output gypsum is scrubbed and dehydrated at the power plant and processed at the gypsum factory adjacent to the power plant or transported to other gypsum factories (six building material factories process the FGD gypsum). Within the FGD unit, the SO2 concentrations of 2,500- 5,000 mg/m3 in the raw gas are reduced to quantities of 30-60 mg/m3. Thus the limit value of 400 mg/m3 is surpassed.