ON OBJECTIONS CONCERNING THE PROBLEM OF UTILIZING THE HEAT OF EXHAUST STEAM FROM STEAM LOCOMOTIVES*

I. N. BUTAKOV

The publication of the article was preceded by a lengthy discussion in correspondence with the organs of the MPS and with individual persons, during which a number of considerations were put forward. Thus, Prof.-Doctor N. I. Belokon, in his first conclusion, wrote: “The coupling of tanks with cold water to steam locomotives for heating this water with exhaust steam, with the subsequent use of the hot water obtained in a low-temperature power cycle—such a scheme is possible; however, the possibility of obtaining fuel savings thereby is doubtful.” It should be noted that in 1943 the question was not of tenders of large capacity—90–100 cubic meters—but of coupling tanks to existing tenders. To prove the doubtful nature of fuel savings in the case of coupling an accumulator tank, Prof. Belokon first constructs a formula intended to determine the monthly saving of fuel of 7000 cal at a power station when switching to a low-temperature cycle without taking heat-supply loads into account:

\[ \Delta B_1 = 24 \cdot 30 \cdot N_{cm} \left( \frac{860}{7000 \cdot \eta^{cm}_{W}} - \frac{G_m + G_0}{G} \cdot \frac{L \cdot 10^{-4}}{W_c} \cdot \frac{b_n}{\eta^{par}_{k}} \right) \cdot 10^{-3}\ t/\text{month}. \tag{1} \]

Here the average load of the power station is \(N_{cm}=300\ \text{kW}\), \(\eta^{cm}_{W}\) is the total efficiency of a depot power station of the ordinary type \(=0.12\), \(G_m\) is the average weight of water in the accumulator tank \(=47\ t\),

\(G_0\) is the weight of hot water in the accumulator tank \(=50\ t\),

\(G\) is the tare weight of the tank, allowing for special equipment \(=23\ t\),

\(L\) is the calculated run of the accumulator tank \(=130\ \text{km}\),

\(W_c\) is the specific production of electric energy in the low-temperature power cycle per \(1\ t\) of hot water \(=720/200=3.6\ \text{kWh}/t\), \(b_n=b_{tkm}=250\ \text{kg}/10^4\ \text{tkm}\), \(\eta^{par}_{k}=0.6\) is the efficiency of the steam-locomotive boiler.

Substituting the above values into formula (1), Prof. Belokon obtained \(\Delta B_1=-200\ t/\text{month}\), i.e., an overconsumption of fuel.

Some inaccuracies were allowed in the calculation presented, namely: the subtrahend was taken for parade running; in order to approximate operating conditions it must be increased by 1.2–3 times (the operating coefficient), and \(\eta^{par}_{k}=1\), since the figure \(250\ \text{kg}/10^4\ \text{tkm}\) should be used only for train operation of a steam locomotive, when the specific consumption of standard fuel is obtained even without \(\eta^{par}_{k}=0.6\) being exaggerated.

\[ b_n = 250 = \frac{2600 \cdot b_e \cdot 0.8 \cdot 130 \cdot 10^4} {60 \cdot 2000 \cdot 130} \ \text{kg}/10^4\ \text{tkm}. \]

Here \(0.8 \cdot 130/60\) is the time of operation of the locomotive under steam (see my article); 2000 is the weight of the train in \(t\), 2600 is the power of the locomotive in hp, whence \(b_e=\)

* Vestnik inzhenerov i tekhnikov, 1947, No. 7.

\(= 1.45\ \mathrm{kg/hp\cdot h}\), whereas for the FD locomotive \(b_e = 1.3\ \mathrm{kg/hp\cdot h}\), and, with feed-water heating, for the SO\(_k\) locomotive even \(b_e = 1.1\ \mathrm{kg/hp\cdot h}\).\(^{1}\) It follows from this that there is no need to introduce \(\eta_k^{\mathrm{steam}} = 0.6\).

Under winter operating conditions without agro-thermal utilization, Prof. Belokon’s formula takes the following form, with corrections inserted:

\[ \Delta B_2 = 720 \cdot N_{cm} \left( \frac{860}{7000} \cdot \frac{1.3}{\eta_W^{cm}} + \frac{\varphi \cdot \Delta t \cdot 10^3}{N_{cm}/200 \cdot 7000 \cdot \eta_k^{cm}} - \right. \]

\[ \left. - \frac{G_0 + Gm}{G} \cdot \frac{L \cdot 10^{-4}}{W_c} \right) \cdot 10^{-3}\ \mathrm{t/month}. \]

After the indicated corrections are introduced, the calculation will lead Prof. Belokon to an overall saving of standard fuel over the year, whereas according to his previous calculation this saving was equal to zero. This saving is obtained on the condition that the fuel consumption for moving the tank is charged to the account of combined energy production, to the account of the low-temperature energy cycle. Meanwhile, as shown in our article, attaching accumulator tanks (more correctly, the use of more capacious accumulator tenders) is caused by the need to improve operating conditions,\(^{2}\) and therefore the fuel consumption for moving the additional quantity of water should be charged to the general interests of railway operation, while the major fuel saving from the proposed production of energy should be a net saving.

Having thus received the proper answer to his first conclusion, Prof. N. I. Belokon advanced a second conclusion, declaring: “Let us examine the idea of using the hot water of accumulator tanks on the broadest basis.” Obviously, the new conclusion says that to heat \(50\ \mathrm{t}\) of water in the accumulator tank, the quantity of exhaust steam that must be delivered into it is

\[ 50 \cdot 10^3 \cdot \frac{100 - 10}{650 - 100} = 8000\ \mathrm{kg}. \]

To preserve the power of the locomotive smoke-exhaust device at the former level, it is necessary to have

\[ 8000 \cdot \frac{1.5 \cdot 0.4 \cdot 10^4}{270 \cdot 10^3} = 180\ \mathrm{hp\cdot h}. \]

The corresponding consumption of standard fuel, with a specific consumption of live steam of \(8\ \mathrm{kg/hp\cdot h}\), is:

\[ \frac{8 \cdot 180}{7000/640} = 131\ \mathrm{kg}. \]

The consumption of standard fuel for moving the accumulator tank is

\[ 250/50 + 23/30 \cdot 10^{-4} = 238\ \mathrm{kg}, \]

and the total fuel consumption is

\[ 131 + 238 = 369\ \mathrm{kg}, \]

which corresponds to a consumption of natural fuel of \(7000\ \mathrm{kcal}\), with boiler efficiency \(0.6\),

\[ B = 369/06 = 615\ \mathrm{kg}. \]

Then, taking as “the most general formula” for solving the question the application of a refrigerating cycle (thermocompression), Prof. Belokon proves that this latter process is more advantageous than heating the water in the tank with exhaust steam.

\(^{1}\) According to data of the Scientific Research Institute of Railway Transport, the consumption of standard fuel per \(10^4\) gross ton-kilometers, depending on train weight, for FD-series locomotives is:

\(^{2}\) Among railway workers in recent years, more and more advocates have appeared for the need to switch to more capacious tenders; among them, for example, Academician V. N. Obraztsov (see Proceedings of the Academy of Sciences of the USSR, Department of Technical Sciences, 1947, No. 10, p. 1401). See also Railway Technology, 1948, No. 1, p. 25.

by the locomotive’s steam. In fact, the amount of heat that can be obtained in a refrigeration installation is

\[ Q=\frac{T_1}{\Delta T}\cdot \eta_2 \cdot AL =\frac{T_1}{\Delta T}\cdot \eta_2\cdot \eta_1\cdot B\cdot 7000 =\frac{368.2}{60}\cdot 0.7\cdot 0.2\cdot 615\cdot 7000= \]

\[ =3.7\cdot 10^6 \text{ cal}, \]

which makes it possible to heat \(3.7\cdot 10^6 \cdot 10^3\,(95-35)=62\ t>50\ t\) of water; moreover, the use of warm water below \(35^\circ\mathrm{C}\) can be carried out without difficulty at all thermal power stations, without any accumulator tanks. Thus, Prof. Belokon concludes, the unprofitability of attaching accumulator tanks to locomotives for heating with exhaust steam is quite obvious, however expedient the subsequent use of hot water may be.

This new conclusion by Prof. Belokon suffers from a number of irremovable paralogisms, namely:

1. No one proposed expending live steam on smoke exhausters when exhaust steam can also be used for this purpose, following the example of CO-type locomotives, directing it after the smoke exhauster into accumulators; thus the term of \(131\ kg\) drops out entirely.

2. As we saw above, there is no need to divide \(238\ kg\) by the \(0.6\) efficiency of the locomotive boiler, since what is at issue is the train fuel consumption, where the norm of \(250\ kg/10^4\ tkm\) must in any case be considered overstated. If these two observations are taken into account, then by thermocompression, under the conditions indicated by Prof. Belokon, it will be possible to heat no more than \(25\ t\) of water, i.e., half as much as with exhaust steam, which is a priori clear to any heat engineer, since thermocompression here has to be realized over such a large temperature interval as \(60^\circ\mathrm{C}\).

3. The coefficient of performance of thermal power stations is taken in the conclusion as \(\eta_2=0.2\), and this is permissible only in the case of current supply from a district thermal power station, whereas ordinary depot stations have at most \(\eta_2=0.1\text{--}0.12\). In turnaround depots, however, thermal power stations are often entirely absent, so that thermocompression is difficult to carry out at all.

4. It is not taken into account that, if a tank is attached, the water will also be heated by exhaust steam in the tender, which is likewise turned into an accumulator. The author of the conclusion, of course, will no longer think of charging the movement of the tender to the low-temperature cycle. We note that heating the water in the tender by thermocompression would require an additional expenditure of energy, which Prof. Belokon did not take into consideration.

5. As indicated in our article, the attachment of a tank—better, the transition to tenders of larger capacity, \(90\text{--}100\ \mathrm{cu.\ m}\)—is dictated by operating interests; therefore the fuel consumption for moving the additional quantity of water should be charged to operating interests, and not to the low-temperature energy cycle.

6. The circulating water from the condensers of thermal power stations, having a design temperature of \(15^\circ\mathrm{C}\) at the inlet, usually has \(25^\circ\mathrm{C}\) at the outlet, and considerably lower in winter, so that such water is of little use for soil heating of cultivation premises; taking this circumstance into account would reduce the effect of thermocompression still further.

From what has been said it is clear what the value is of Prof. N. I. Belokon’s conclusions. Let us now turn to consideration of the other objections that have been received.

It was pointed out that the production of energy in utilization turbines is determined by the quantity and temperature of the water entering their evaporators, whereas the demand in kWh depends on consumers and may not coincide at all with their output. But this objection is characteristic of all cases in which electricity is generated on the basis of heat consumption. In these cases it is obligatory

an additional condensing installation ensuring coverage of the deficient capacity. Such installations exist in many depots, and some depots receive current from the power system. The depots’ own installations will be placed under better operating conditions, since the possibility will be provided of obtaining distillate for feeding their boilers from the condensers of the utilization turbines.

It was further pointed out that, from the standpoint of fuel consumption, it is much more advantageous to receive current on the depot territory from some external (district) power station than to organize the proposed use of a low-temperature cycle. Let us consider this objection as well. The efficiency of even our best district power stations (ShGES, ChGRES, Kashirskaya, etc.) does not exceed 23%, so that, allowing for losses in the networks and the station’s own requirements, we find the efficiency at the point of consumption to be about 20%.¹) Taking the average annual capacity of the utilization installation as 300 kW, we obtain an hourly fuel consumption of \(300 \times 860 / 0.2 \times 7000 \times 10^3 = 0.18\) t. In addition, the heat consumers will take \(8.5 \times 10^6 / 0.5 \times 7000 \times 10^3 = 2.43\) t, and altogether 2.61 t/h, which, at 8760 annual hours of operation, gives a saving of standard fuel of about 23,000 t. Those objecting here (and these are electrical engineers) have chiefly in mind electric power, forgetting the heat consumers, who are the principal spenders of fuel—not to mention the fact that here the saving of fuel from the non-stop movement of trains, from the use of water purification, and at water-pumping stations, the fuel saving due to the use of more capacious tenders, is completely ignored.

Some of those raising objections were perplexed as to how regulation of the supply of heat to subscribers could take place when the temperature of the outside air changes. Of course, in the present case regulation is possible only quantitatively, since the temperature of the water in underground reservoirs remains constant at 90–95°C. Assuming that the velocity of water in the pipes can vary from 0.5 to 2.5 m/s, we can vary the quantity of heat supplied by a factor of five. With a further decrease in the demand for heat, it is necessary to proceed to regulation by shutoffs. The surplus water obtained under the indicated forms of regulation, at a temperature of 90–95°C, must be directed to the higher-pressure part of the utilization turbines in order to increase the generation of electric power. It follows from this that, in view of the variable quantity of water entering the utilization turbines, the latter should not be installed at full capacity (500 kW) in a single unit; rather, the full capacity should be divided among turbines of smaller capacity, switched in as needed. The question of standardizing the capacity of utilization turbines is a special question requiring additional study.

The indication of the excessive complexity of the chain for utilizing the heat of the exhaust steam of locomotives also seems unconvincing. All links of this chain and of its stationary part have been tested by previous practice. Thus, heating water networks in the USSR already have a history of many years, and in the present case there is nothing specific in them; utilization vacuum turbines have been tested by practice²); soil heating in greenhouses with the use of clay pipes has been tested under our conditions.³) Tre—

¹) The weighted-average net efficiency of the main electric systems (condensing and district-heating) in our country, according to reporting data, ranged from 15 to 21%. Economy of Electric Power in Industry, 1947, ch. 1, (V. I. Veits), p. 15.

²) Our preliminary designs showed that utilization vacuum turbines in this case are simple in construction, will have one or two shrouded disks, and, one may suppose, can be manufactured at the same plants where the smoke exhausters and lighting turbines now used on our locomotives are produced.

³) I. M. Ibryaev, “Possibilities of Agro-District Heating,” Teplo i sila, 1936, No. 5.

...only to compensate for the possible asynchronism between the arrival of trains with heat accumulators and the consumption of hot water from underground reservoirs, which must be designed as a compensating intermediate capacity. If we trace the progress of modern industry, we shall everywhere see a lengthening of the chains in which primary raw materials are used. As is evident from our article, preliminary economic calculations justify the possibility of capital investments, with an ample surplus sufficient for carrying out the necessary work.

In Vol. III (p. 20) of the textbook Heat-Power Economy of Railway Transport it is quite correctly stated: “Under the conditions of railway transport, heat supply should become widespread.” A number of railway authors dream of installing, during the five-year period 1946–1950, turbines with a back pressure of 200–300 kW at depot stations, with extensive development of centralized heat supply for railway junctions. Thus the question of heat networks for depot stations is fully ripe, and such networks will, sooner or later, have to be laid in any case. Difficulties with pipes will soon be overcome, since already in 1950 their output is planned in the amount of 1.5 million tons. Greenhouses, too, will have to be built in order to provide the army of railway workers and nearby populated places with fresh vegetables all year round; moreover, the difficulties due to the absence of glass will quickly pass, since in 1950 glass production will increase 1.8 times compared with 1940. All this can proceed in the order of any desired gradualness, over any number of years, according to a definite plan.

The thought was also expressed that attaching a tank car or introducing tenders of large capacity would force a reduction in the weight of trains. But, as a rule, the power of locomotives is not used fully, and many years of experience have shown that an increase in the amount of water carried has not affected the weight of trains¹.

It was also advanced as an objection that an increase in the capacity of the water supply at depot stations would be required.

Since, along the route, as the calculations given in the article show, about half the water reserve in the accumulators will be consumed, while the other half, having completed its cycle of using low-temperature heat within the depot territories, will return with the possibility of refilling its accumulators, the depot station will consume the same amount of water as at present for filling tenders; i.e., apparently, no increase in the water supply should be required². Nor, one must suppose, will the development of traction tracks and depot buildings be required, since the increase in section speeds and the introduction of chemical water treatment will greatly improve locomotive turnover, so that servicing the traffic will become possible with a smaller number of them, which should free part of the existing space in depots. Fan-shaped de—

but, of course, may require reconstruction, as will turntables where there are no wyes. But this is unfortunately inevitable under all conditions as the power of locomotives increases, and during the existence of railway transport in our country such reconstruction has already been carried out more than once.

Some have noted that draining water from larger tenders and filling them with water may increase the time locomotives spend under servicing, which will affect their turnover. Meanwhile, it cannot be denied that this can be avoided by combining the phases of servicing operations, by designing the servicing installation accordingly, which in most cases has hitherto suffered from a lack of forethought.

Then there were objections that feedwater from accumulators would contain lubricant, which is harmful to locomotive boilers. But, first, the lubricant will be in a larger mass of water than is now the case in the condensers of class SOk locomotives, and therefore conditions here will be more favorable than in these latter locomotives; second, the practice of using exhaust steam from hammers in stationary installations has shown the expediency of applying an absorbent of the aluminum-oxide hydrate type, \(Al(OH)_3\), to free the water of lubricant residues after mechanical oil separators.

Another objection was that supplying steam to the accumulators requires flexible connections, which are not very reliable in service, and that in order to avoid cooling of the water in the accumulators en route and during stops special measures would have to be taken. But if one tank car is coupled to the locomotive, or if a more capacious tender is used, then the more water is cooled in these accumulators, the better: less steam will escape into the cone and more heated water will be delivered to the depot. Designing flexible connections presents no difficulty, since the pressure of the exhaust steam is low. Uncoupling, coupling, and connection to the exhaust pipe will not be required each time, since the locomotive tender, as a single unit, must be supplied to the servicing devices and to the depot.

Finally, there was also the objection, made at one of the author’s reports by a coal-specialist professor, that one ought not to deal with the steam locomotive, since the railways will be electrified. He had to be reminded that the steam locomotive remains the principal engine in railway transport; that the annual output of steam locomotives by plants in the USSR in 1950 is brought up to 2,200, while that of electric locomotives is only up to 220.^1 After all, he does deal with shields in coal mining, instead of dealing with underground gasification of coal. The development of Soviet power engineering, by decisions of the Council of People’s Commissars in 1927, of the Central Committee of the All-Union Communist Party (Bolsheviks) in 1931, and of the Eighteenth Congress of the All-Union Communist Party (Bolsheviks) in 1939, is directed along the path of broad introduction of district heating; moreover, the Eighteenth Congress of the All-Union Communist Party (Bolsheviks) demanded a resolute struggle against gigantomania and a broad transition to the construction of small and medium thermal power stations of 25 MW and below, condemning as improper and harmful to the national economy the infatuation with large power stations. In this respect, the use of the steam locomotive as a mobile steam-power installation of small capacity, in combination with its use for district-heating purposes at railway depot stations, should attract our special attention. Judging by the report of the State Planning Committee of the USSR at the first session of the Supreme Soviet of the USSR, in connection with the Five-Year Plan for 1946–1950, the question of applying internal-atomic energy in transport is being placed on the agenda as a promising new technology. The energy resources of transport have always been autonomous, and undoubtedly, according to the laws of dialectics, the future belongs to them as well, whatever

^1 Law on the Five-Year Plan for the Restoration and Development of the National Economy of the USSR for 1946–1950.

were intermediate stages of development, the passage through which, as is known, is not always obligatory: it is always possible to move to a higher stage while bypassing the intermediate one. The preservation of autonomy is dictated by strategic considerations as well, by the entire international situation. Therefore, from this point of view as well, at the present stage of development the steam locomotive, it turns out, must be the principal engine of railway transport; but, of course, we must take from it everything that it can give. And it can still give a great deal.

Many metaphysicians consider their proposal firmly substantiated merely because they have victoriously refuted the objections that were raised against the proposal, and they rest content with this; that is, they substitute the certification of the proposal’s having been proved with the certification only of its irrefutability. This characterizes the well-known logical error called substitution of proof (ignoratio elenchi). The author would not wish to fall into this error. He therefore believes:

1. The discussion must continue; new objections must be heard.

2. It is necessary now to begin developing the design specification as applied to some specific section of railway. Practice is the best criterion of truth. In the course of work on the design specification, difficulties not now foreseen can and must come to light; but, one must suppose, means will also be found to overcome them. The development of the design specification is beyond the powers of one person; here an entire team is required, as well as funds to pay for its work. This is precisely what the author does not yet have at his disposal.

1. Rolling Stock of the Railways of the USA. Moscow, Transzheldorizdat, 1941, p. 85. From the report of Prof. N. I. Nikolaev at the Scientific and Technical Council it is evident that on the most heavily loaded directions the adhesion weight of locomotives is underutilized, and boiler forcing is reduced to 20–30 kg/m²·h. Railway Transport, 1947, No. 1, p. 37.

   The absence of full utilization of the tractive power of locomotives is also attested by the article “Ensure a New Upswing in the Work of Transport in 1949” in the journal Railway Transport, 1949, No. 1, p. 9, where it is rightly noted that the best confirmation of the existing reserves in the matter of increasing train weight is the movement of locomotive drivers—heavy-haul operators.

   In the prewar period, the average utilization of the lifting capacity of the wagon fleet on our railways was only 77.5%; i.e., on average 22.5% of a wagon’s lifting capacity was underutilized. Reserves of Railway Transport. Transzheldorizdat, 1946, p. 20. ↩

2. The introduction of more water-capacious tenders would make it possible not to think about major capital investments for work to strengthen the water supply at intermediate stations for the purpose of speeding up water intake by locomotives and reducing stops, as is written, for example, by S. F. Goncharov (Railway Engineering, 1948, No. 8, p. 5). ↩