DEGRADATION OF THE TRADITIONAL CYCLE OF THE SECOND REGION IN THE DOMESTIC ENERGY SECTOR

S. V. Polozhii

(Presented by the scientific seminar of the Department of Thermal Power Plants)

Domestic power engineering at the present stage, in the development of condensing power plants, is following the American path of development. The United States was the first to switch to the use of the traditional steam-turbine cycle of the second region; it was also the first to adopt erroneous decisions in the initial period, moving to the construction of units with very high initial steam parameters of 350 ata, 650°C with one and two reheats of steam, which were economically inexpedient, operationally unreliable, practically unmasterable, and then abandoning the further construction of such units and moving to the mass introduction of units with reduced steam parameters of 240 ata, 538/538°C, which subsequently became the world standard for the steam parameters of unit thermal power stations in the power engineering of highly developed countries. The United States, earlier than other countries, oriented the development of power engineering toward the construction of units of enormous capacity, up to 800–1200 MW; it mastered them well and achieved their design performance indicators in base-load operation. Power engineers in the United States were the first to become convinced of the unsuitability of operating base-load units in variable mode to cover the semi-peak load, and they began intensively introducing maneuverable thermal power stations of low thermal economy for the variable part of the load curves of power systems.

In the U.S. power industry, for the first time in the world, the main contradiction of the traditional cycle of the second region manifested itself with complete obviousness—the incompatibility of unit thermal power stations with the conditions and requirements of power-system operation in variable mode, as well as the erroneousness of planning decisions about a continuous reduction in the specific fuel consumption from the mass introduction and successful mastering of advanced, highly economical base-load units with the traditional steam-turbine cycle of the second region. Empiricism in domestic power engineering is manifested no less than in the power engineering of the United States. In some cases, domestic power engineering took into account the experience and erroneous technical decisions in U.S. power engineering; in others, it did not. The development of unit thermal power stations in our country began with lower steam parameters—130 ata, 565/565°C, units of 150 and 200 MW. In our country, the recommendations of a significant portion of the scientists of the 1950s concerning the construction and introduction of units at 350 ata, 650/650°C, which were then being operated and mastered in the United States, were not adopted. Thus it was possible to avoid the catastrophe that would have been caused by such an unrealistic development of unit thermal power stations in our country. Now this is clear to everyone. In other cases, domestic power engineering neglected the world stan-

standard for the initial steam temperature in high-capacity supercritical-pressure units at 540°C, while maintaining it at a high level of 565°C in large-capacity units until 1971. In the power industry of our country the experience of the USA in ensuring operating reliability was not taken into account in good time—namely, the need to develop maneuverable units with reduced steam parameters and thermal efficiency for semi-peak and peak loads of power systems (Fig. 1) [11].

Fig. 1. Structure of generating capacities and transfer of base-load subcritical- and supercritical-pressure units to the variable part of load schedules in U.S. power systems (forecast for 1980–85 [11]):
1 — reactive GTUs; 2 — combined-cycle plants; 3 — thermal power plants; 4 — nuclear power plants.

For a long time in our country there prevailed an unjustified optimism in assessing the possibilities for rapid mastering of 300 MW supercritical-pressure units at 560/565°C, which led to the mass introduction of difficult-to-master units in the country’s power systems. Later than in the USA, the conclusion was reached that it was unpromising to raise the initial parameters above 240 ata, 540°C. Two or three years ago, and even at the present time, recommendations were still being made for a further increase of the initial parameters in our country to 300 ata, 650°C.

The domestic power industry, in the mass introduction of unit thermal power plants, did not take into account the problem of peak capacity, the rational structure of generating capacities for the European part of the country (Fig. 2). The entire period of construction of unit thermal power plants in the past and at present in our country is characterized by the production of generating capacities only for base load, justified only for a large number of hours of utilization of installed capacity, such as units K-160-130, K-200-130, K-300-240, power equipment for CHP plants and nuclear power plants.

For the Ninth Five-Year Plan, production and construction were likewise planned only for base equipment, completely unsuitable for operation in the variable part of electric-power-system load schedules. For this reason, already at the present time a large gap has arisen between base-capacity thermal power plants and the available base load of the Unified Power System of the European part of the USSR [1, 2]. According to the load of the Unified Power System of the Center and North-West, 57% of base thermal power plants are required, whereas 74.8% are available; semi-peak thermal power plants require 22%, whereas 7.7% are available. The development of CHP plants in our country is not considered a factor reducing the base load—

Fig. 2. Transfer of base-load subcritical- and supercritical-pressure units to the variable part of load schedules of USSR power systems (forecast for 1985 [12]):
a — main variant; b — rates of commissioning of CHP plants reduced; c — rates of commissioning of nuclear power plants reduced; d — increased transfer of electric power from Siberia. Initial — initial variant; I — first five-year period; II — second five-year period; III — third five-year period. 1 — units K-100-90; 2 — subcritical-pressure units K-200-130; 3 — supercritical-pressure units K-300-240; 4 — supercritical-pressure units K-800-240.

load for high-efficiency condensing district power station units. In the UES, more than 30% of all installed capacity is accounted for by CHPPs, which is used only in the base part of the power-system load curves, reducing by this amount the base load for condensing district power stations with units operating at medium and supercritical steam parameters.

The long period of mastering 300 MW supercritical units, the high reduced calculated costs of electricity production, along with low reliability [3, 4, 13, 14, 15] (Tables 1 and 2), did not make it possible to accumulate experience and identify the degradation of the traditional cycle of Region II during the period when power systems were operating with well-mastered units, nor to take in good time the necessary technical measures, especially for the development and introduction of maneuverable thermal power plants to cover the variable part of the load curve of electric power systems. This has placed the work of the power systems, both in terms of efficiency and in terms of reliability of electricity production in the UES [5], under difficult conditions. For this reason, solving the problem of peak capacity in the Unified European Power System has acquired the greatest state importance. The solution of this problem proved to be unprepared, and its formulation unexpected [5]. Only in 1970, judging from the literature, were studies begun in this area and tasks outlined for its solution, which, it turns out, can be carried out no earlier than in the following five-year plans, in view of the large backlog in the development of base-load unit district power stations, CHPPs, and NPPs in the Ninth Five-Year Plan.

In the opinion of the USSR Ministry of Power [6], until 1980 there is no other solution except to increase the maneuverability of the 300 MW supercritical power units being produced, and all tasks connected with this must be solved in the shortest possible time. At present, because of the technical impossibility of operating K-300-240 supercritical units in a variable mode in the UES, it is necessary to generate a large amount of electricity on these units in base-load mode using expensive imported fuel, and to transmit this energy to regions with cheaper fuel—in the direction opposite to the fuel-transport flow—from the North-West and the Center to the power systems of the South and South-East. This leads to a substantial increase in calculated costs and in fuel consumption for power generation. Such an irrational structure of generating capacities in the UES, which is acquiring a threatening significance, is the result of the failure to identify the law of degradation of the traditional cycle of Region II in the domestic power sector.

The degradation of the traditional cycle of Region II in the domestic power sector over the past decade has manifested itself in the difficulties of mastering 300 MW supercritical units [3–5], in the inability for a long time to achieve the design operating indicators of such units, in the small number of hours of utilization of installed capacity, in high specific fuel consumption and especially in high calculated costs for electricity production by supercritical unit installations, as well as in the low reliability and high accident rate of such units. The absence of special maneuverable thermal power plants in our country intensifies to an even greater degree the negative effect of the degradation of the traditional cycle of Region II. The transfer of 200 and 300 MW base-load units to semi-peak load has not been technically prepared, is not economically expedient, and is unsuitable operationally [1–3, 5].

Operation of the K-200-130 base-load unit in semi-peak mode increases the costs of electricity production for regions using expensive fuel from 0.9 in base-load mode to 1.94 kopecks/kWh with 2000 hours of operation per year and to 1.34 kopecks/kWh with 4000 h/year. At the same time, the specific fuel consumption for each kilowatt-hour generated in semi-peak mode

Economic indicators of operation of SKD K-300-240 units [13] for 1965–67, in connection with the degradation of the traditional cycle of the second region at the stage of unit development

Table 1

* On average, the operating indicators of the K-300-240 units below the design values for 1965–67 were: the specific heat consumption for electricity generation was 15%; the working-time utilization factor was 24.5%; the installed-capacity utilization factor was 23%. Heat consumption for auxiliary needs was higher than calculated by 2.6%. According to the design indicators of the SKD K-300-240 turbines, it should have been, by comparison with K-100-90 turbines of specific weight by a factor of two and labor intensity by a factor of 1.5, lower. In practice, owing to prolonged development of the K-300-240 units, it was 34% higher on the fifth year than the design value.

Table 2

Design and operating data on the cost of one kilowatt-hour supplied
for SKD K-200-130 units [13]

increases from 30 at 400 h/year to 70 g/kWh of standard fuel at 2,000 hours of operation per year, with an absolute specific fuel consumption of 380–400 g/kWh instead of 330 g/kWh under base-load operation [5]. The introduction of special maneuverable units with traditional cycles and power equipment is aimed primarily at ensuring the reliability of power-system operation and, along with this, makes it possible, with reduced steam parameters and simplified thermal schemes, to substantially reduce the calculated costs of producing electric power in the semi-peak part of power-system load curves compared with transferring base-load units into this part of the load schedules (Fig. 3), if the base-load SKD units were technically suitable for operation in the semi-peak part of the load curves of electric power systems.

The calculated costs of producing electric power by special maneuverable steam-turbine thermal power plants and gas-turbine power plants, at 2,000 hours of operation per year, are 0.2–0.5 kopecks/kWh lower than for base-load K-200-130 units and 0.1–0.08 kopecks/kWh lower at 4,000 hours of operation per year. The thermal economy of maneuverable semi-peak thermal power plants and gas-turbine stations, however, proves to be significantly lower than that of base-load units when they operate in semi-peak mode. The specific fuel consumption at such maneuverable thermal power plants, depending on the number of hours of operation per year, is 450–500 g/kWh [5]. In modern electric power systems, more than half of electric-power production falls on the variable part of the load curves in the power systems of the Unified Energy System of our country. Electric-power production in the sharp-peak part of load curves is characterized by even higher specific fuel consumption.

The intensive introduction of nuclear power plants into the Unified Energy System will, in the future, lead to the complete displacement of unit-type thermal power plants and combined heat-and-power plants from the variable part of power-system load curves (Fig. 2), with a small number

hours of utilization of installed capacity, which is expensive and economical in base-load operation, with shutdowns at night and on weekends, operation at low loads, and frequent starts and shutdowns of units; this will cause a sharp reduction in the operating efficiency of unit-type thermal power plants and nuclear power plants as a whole in future power systems and will lead to the final degradation of the traditional cycle of the second region in domestic power engineering. In this case, the problem of peak capacity and the variable operating regime of nuclear power plants will increase to an even greater degree, and the need to introduce special maneuverable steam-turbine and gas-turbine power plants, uneconomical in terms of fuel consumption, will become still more acute.

Modernization of base-load supercritical-pressure units for operation in a semi-peak regime, if a technical solution can be found for creating maneuverable supercritical-pressure units with the traditional cycle of the second region, will lead to an additional increase in the cost of supercritical-pressure units compared with the base-load supercritical-pressure units currently being produced, as well as to an additional reduction in thermal efficiency and to still higher calculated costs and specific fuel consumption in the variable regime compared with the operation of modern base-load units in a semi-peak regime. In this connection, the development of thermal power engineering in terms of steam parameters, thermal efficiency, and, even more so, calculated costs will move backward—along the path of reducing the efficiency of electricity production instead of the assumed and planned continuous increase in the efficiency of energy production in future power systems with the traditional cycle of the second region. From lofty intentions, brilliant forecasts of achieving low calculated costs for the production of electric power, and the transition of power engineering to unit-type base-load supercritical-pressure thermal power plants in the near future, a reverse process is taking shape—the reduction of the efficiency of the power industry with the expenditure of enormous funds and material resources on scientific research, development, introduction, and assimilation of new equipment, while overcoming complex problems and great difficulties associated with the conditions of variable operation of thermal power plants in power systems.

Neither the high level of power-machine building, nor comprehensive automation and optimization of the construction and operation of power plants and power systems, nor many other achievements in power engineering and other branches of production are capable of stopping or preventing the final degradation of the traditional cycle of the second region, the historicity of its development with the complete transfer of fossil-fuel thermal power plants to the variable part of the load schedules of future power systems. This entire process in domestic and foreign power engineering is proceeding without disclosure of the basic law of the traditional cycle of the second region, without a profound understanding of the negative consequences for the development of the power engineering of the future of present-day technical decisions in the field of thermal power engineering [1–10].

The great achievements of Soviet power engineering over the past decade [8], the high qualitative and quantitative indicators of electric-power production, and the rapid pace of power construction, ensuring at all stages of the development of the national economy the technical re-equipment of all branches of production, are the result of the socialist economic system, the high scientific and technical level of development of our country, and the intensive activity of the scientific-technical and production potential of domestic power engineering. It is especially noteworthy that these achievements of domestic power engineering have been attained within the framework of the traditional cycle of the second region, which required the solution of extremely complex and difficult technical problems and high

organization of scientific research, design and engineering work, a high level of development of power engineering, metallurgy, and other branches of the national economy, as well as the concentration of material and production resources. These achievements became possible thanks to the concentration of generating capacities and the centralization of power supply in our country, carried out throughout the development of domestic power engineering and especially during the last decade—the decisive factor of technical progress along the traditional path of power-system development.

Fig. 3. Calculated costs for producing electric power at various types of power plants as a function of their annual number of hours of utilization [5].
1—NPP; 2—supercritical-pressure units K-800-240; 3—supercritical-pressure units K-200-130; 4—supercritical-pressure units K-500-160; 5—maneuvering units at 90 atm, 500°C; 6—aircraft jet gas-turbine units, 54 MW; 7—gas-turbine units with specific capital investments of 70 rubles/kW; 8—gas-and-steam plant with specific capital costs of 170 rubles/kW (cheap fuel).

The concentration of electric-power production in our country made it possible to accelerate the build-up of capacities, reduce the specific volume of the construction part of thermal power plants, increase labor productivity and the efficiency of the use of capital investments, increase the output of equipment by power-engineering plants, and improve the technical-and-economic indicators of electric-power production.

At the beginning of 1972, the capacity of large units in our country amounted to more than 40% of all units installed at thermal power plants [9]. The total capacity of state district power plants in the range of 1–2.4 million kW exceeded 35% of all thermal power plants in the country. The transition to 800 MW units in the next five-year plan may lead to savings of monetary resources on the order of 8 rubles for each kW of installed capacity and reduce the specific fuel consumption by 6 g/kWh for ...

compared with 300 MW units for the same steam parameters. The proposed commissioning of 40 units of 800 MW over the next 10 years will make it possible to save 250 million rubles and 1,150 thousand tons of standard fuel per year [9].

Even more effective has proved to be the concentration of production in the combined generation of electric power at CHP plants through the introduction of large power units and the construction of high-capacity CHP plants. The transition from CHP plants of 100 MW capacity to CHP plants of 300–1000 MW and higher has led to a reduction in capital investments by 70–80 rubles/kW.

Fig. 4. Dependence of the relative cost of electric-power generation on the annual number of hours of utilization of power plants. 1 — nuclear power plant, nuclear fuel, 21 grades of FRG/t standard fuel; 2 — thermal power plant, brown coal, 35 grades of FRG/t standard fuel; 3 — thermal power plant, hard coal, 91 grades of FRG/t standard fuel; 4 — thermal power plant, gas–fuel oil, 49 grades of FRG/t standard fuel—gas, 63 grades of FRG/t standard fuel—fuel oil; 5 — thermal power plant—AF, brown coal, according to TPI data. (Specific capital investments of thermal power plants on brown coal are 15% higher, and on gas–fuel-oil fuel 12% lower, than those of thermal power plants on hard coal. The specific capital investments of nuclear power plants are 70% higher than those of gas–fuel-oil thermal power plants). 1–4 — for FRG conditions.

The daily schedule of electricity consumption in the Unified European Power System has a pronounced peak character, especially in the Unified Power System of the Northwest, the Unified Power System of the Center, and the Unified Power System of the South. In the prospective development of the Unified European Power System, the problem of covering the variable part of load schedules becomes especially acute, as does the problem of the optimal choice of the composition of generating capacities.

According to data from Energosetproekt [9], to cover the variable part of load schedules on the scale of the Unified European Power System in 10–15 years it will be necessary to commission up to 10 million kW of gas-turbine units, to double hydropower plants through the construction of pumped-storage plants, and to install up to 15 million kW of special maneuverable steam-turbine thermal power plants of low thermal efficiency with subcritical steam pressure, capable of being shut down daily and quickly brought into operation, as well as to unload part of the high-capacity supercritical-pressure units at night by 30–50% of nominal capacity (Fig. 2 [12]). At the same time, the construction of maneuverable units alone will yield a saving in capital costs of 210 million rubles in comparison with operation of base-load supercritical-pressure units of the same capacity at equal (low) thermal efficiency in the variable part of the load schedules of the compared units. The operation of gas-turbine units and pumped-storage power plants leads to an even sharper increase in specific fuel consumption and calculated reduced costs for the production of electric power than would have occurred with operation of units in base-load mode with the traditional cycle of Region II (Figs. 3, 4).

These data may serve as a certain illustration of the degradation of the traditional cycle of Region II in the Unified European Power System of our country over the next 10–15 years, and also confirm the conclusions of TPI regarding the absence, in modern literature reflecting technical policy and forecasting of the energy sector of the future, of a sufficient conception of the objective law of development of power engineering.

The successes achieved in the development of the domestic power industry through the concentration of generating capacities and the centralization of power supply, in view of the degradation of the traditional cycle of the second region, prove in fact to be extremely overstated. The high efficiency and progressive role of the concentration of generating capacities and the centralization of power supply cannot be realized in a power industry with modern steam-turbine installations of SVD and SKD, and they are almost entirely expended on overcoming the numerous shortcomings in the development of the power industry with the traditional cycle of Region II at the stage of its degradation.

In the near future, in 10–15 years, with the complete transition of large base-load unit thermal power plants of SKD to the variable part of power-system load schedules, the concentration of generating capacities, even at its present level, will lead not to an increase but to a decrease in the efficiency of electric-power production in power systems; from a progressive factor it will become a regressive factor in the development of the power industry with the traditional cycle of Region II at the stage of its final degradation [10].

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