US1962574A - Marine high pressure superheated steam plant - Google Patents

Description

June 12, 1934. w SALGE 1,962,574

MARINE HIGH PRESSURE SUPERHEATED STEAM PLANT Filed Jan. 17, 1930 M ap/5 2 E l/7x.

Patented June 12, 1934 UNITED STATES MARINE HIGH PRESSURE STEAM PLANT Wilhelm Salge,

SUPERHEATED Berlin, Germany Application January 17, 1930, Serial No. 421,549 In Germany January 22, 1929 1 Claim.

This invention relates to a marine high pressure superheater which enables the heat of the high pressure steam to be economically utilized in the main multi-stage steam engine, in the aux- 5 iliary engines and in other arrangements for heating purposes.

Although the advantages of the use of superheated high pressure steam and the advantages of the use of multi-stage steam engines, more particularly those of the Woolf type, are known, there are difliculties as regards their employment on board ship, when the high pressure steam boiler supplies superheated steam of far higher ,temperature than a reciprocatingmarine engine can stand up to with safety.

The invention enables the two arrangements to be used together as well as any other auxiliary engines and heating arrangements in spite of this difierence in temperature which is undesirable in 20. itself. This is effected by various interdependent operations. In the first place, when using a two or multi-stage main engine, the steam withdrawn from the high pressure boiler is delivered to a temperature regulator which lowers the inlet temperature'of the steam for the high pressure part of the plant and increases the volume of the exhaust steam of the high pressure part carried away by it to such an extent that the low pressure part is driven with the same power as the high pressure part and that in addition to this a quantity of steam is obtained for producing external power, for instance for driving auxiliary engines and for. operating heating arrangements.

Furthermore in order to render the driving of the auxiliary engines and the operation of the :bther arrangements independent of the power fluctuations of the main engine the steam obtained by the increase in volume is supplied to a low-pressure steam accumulator which is sup.- plied automatically from. the boiler with steam, the pressure of which has been several times reduced.

In order to enable the high pressure superheater plant to be operated economically, even in cases in which when manoeuvring with a small admission there would be an unequal distribution of the power in the individual cylinders of the main engine, a direct connection is provided between the steam space in the boiler and the high pressure cylinder of the first stage, for maintaining the equal distribution of power, which connection enables mixed'steam to be supplied. A particularly suitable arrangement has been found to be that in which two compound engines of the Woolf type are usedone behind the other.

For further increasing the economical working of the plant a multi-stage feed water heater is used which is heated by exhaust steam or tapped steam being used as the heat carrier, the temperature of which is only so much higher as is necessary for an economical dimensioning of the heating surfaces without a greater temperature drop than necessarybeing expended.

For clearly illustrating the invention a diagrammatic view of the new high pressure superheater arrangement is shown in the accompany- -ing drawing, the super-pressures, temperatures and quantity of circulating steam being given in a numerical example.

In the drawing A is a water tube boiler containing a high pressure superheater B. In the example shown the main engine is a multi-stage reciprocating steam engine which is divided into a high pressure part C1 and a low pressure part C2. Both parts of the plant work on a common crank shaft. It has been found particularly suitable to place two compound engines of the Woolf type one behind the other, each engine having two pressure stages C1 and C2 placed one behind the other. The high pressure steam withdrawn from the superheater B is first passed through the pipe a to a temperature regulator D by which the steam is cooled down to the temperature which is most economical for the high pressure part C1 and is suitable for reliable working, whereupon it flows through the pipe b to the high pressure part. The cooling medium used is the exhaust steam leaving the low pressure cylinder of the high pressure part C1 through the pipe. 0.

This exhaust steam absorbs inthe temperature regulator D the heat previously withdrawn from the high pressure steam, whereby its temperature is raised and its volume thereby increased to such an extent that the steam supply through the pipe d to the low pressure part C2 produces in the latter with a smaller quantity as regards weight, the same power as in the high pressure part C1 with a larger quantity as regards weight and that through the increase in volume referred to a volume of steam is obtained for producing an external power, which volume is branched off through the pipe e for driving auxiliary engines or for operating other heating arrangements.

The pipe 6 may be connected directly to the points of withdrawal. As, however, it is impossible in operating a ship to keep the quantity of steam supplied to the main engine and its pressure such that the quantity of steam withdrawn and its pressure will continuously correspond to the working conditions of the attached auxiliary engines and auxiliary arrangements, the quantity of steam obtained by the increase in volume is supplied in the first instance through a nonreturn valve E to a low pressure steam accumulator F. This low pressure steam accumulator F also receives steam from a high pressure steam accumulator G. The two accumulators are connected to one another by a pipe f containing a reducing valve H.

The high pressure steam accumulator G is itself supplied from the high pressure boiler A through the pipe g with steam, the pressure of which is suitably reduced by a reducing valve J.

The high pressure steam accumulator G can also supply through a pipe 2' an auxiliary engine K (for instance a lighting machine) with working steam, the exhaust steam of this auxiliary engine being led through a pipe is to the low pressure steam accumulator F.

On load fluctuations occurring at the main engines, more particularly when manoeuvring or when travelling at a slow speed, the low pressure steam accumulator will receive from the boiler by way of the high pressure steam accumulator and through an automatically operating regulating device so much steam with its pressure several times reduced that the quantity of steam required in the low pressure steam accumulator and the suitable pressure for the operation of the attached auxiliary engines and arrangements will remain constant.

For working economically with high pressure superheated steam on board ship special attention must be paid to the heating of the feed water. In order that the boiler shall have a very high efficiency it is so constructed that the feed water is fed to it at as high a temperature as possible.

This is efiected by using a multistage feed water heater L, the lower stages of which are fed in a known manner with condensates and exhaust steam from the auxiliary engines or the low pressure part, the later higher stages receiving steam from that part of the plant, which lies in front of the low pressure part of the main engine.

In the example shown the first stage of the feed water heater is heated by the exhaust steam coming from one auxiliary engine (for instance the steering engine), which is led to this stage through the pipe Z. The second stage of the feed water heater receives through the pipe m a portion of the steam of the auxiliary engine M which 7 receives its working steam through the pipe n from the low pressure steam accumulator F. The third stage is heated by means of the pipe 0 by steam withdrawn from the pipe 0 conveying the exhaust steam of the low pressure cylinder of the high pressure part C1 to the temperature regulator D. Finally, the fourth stage of the feed water heater is heated by means of the pipe 17 by a portion of the exhaust steam of the high pressure cylinder of the high pressure part C1. In addition thereto the condensate of each separate stage can be utilized for heating the preceding stage or the first stage. This is effected by means of the connections n, 12, 1'3.

This arrangement enables the feed water to be heated up very highly in uniform succession.

As is well known, marine engines must, when manoeuvring and at slow speeds, frequently work with small admissions. When using high pressure superheated steam, this has the disadvantage that with the smaller admissions the power distribution in the individual cylinders becomes unequal, as the pressure of the superheated steam in the highpressure stage sinks so low that the power in the second cylinder of the high pressure stage becomes considerably smaller.

In order to overcome this disadvantage when manwuvring with smaller admissions and to make full use of the advantages of the high pressure superheated steam plant in this case as well, the engine is driven during this relatively short working period with mixed steam. This purpose is served by a pipe 8 which is branched off from the boiler A and connects up to the pipe b. In this case the expansion in the high pressure cylinder drops far less rapidly than when superheated steam is used and a uniform power distribution in the two cylinders is thus ensured when manoeuvring as well. This is absolutely essential for the smooth vibrationless working of reciprocating steam engines, more particularly for the propulsion of ships.

By the supply of saturated steam which mixes with the superheated steam coming from the regulator D, the exhaust steam escaping from the low pressure cylinder of the high pressure part of the plant will be wet steam. It will however be immediately reconverted in the temperature regulator into dry or superheated steam.

In the high pressure saturated steam plant just described it is possible to increase the heat utilization in steamers and the economy in driving to a maximum. The advantage which can be obtained through the invention is particularly apparent when comparing the calories per horse power hour required for plants of a known type of the best construction. Including the consumption of the auxiliary engines required for operating the particular plant the following calories are required:

1. With simple steam engine plants working with a normal pressure (131'l atm.) normal temperature (280-325 C.) with a double, triple or quadruple compound engine 3800 to 4200 calories.

. 2. With a modern steam engine plant with the same pressure and superheated steam, using for instance Lentz unitary marine engines, about 3500 calories.

3. With a steam turbine drive for larger ships operating with high pressure and superheated steam, about 3200 calories.

4. With a Diesel engine drive, about 2200 calories.

The drive involving the lowest running costs is of course that to be aimed at. It should be kept in mind that the oil calory costs on the average 3.4 to 4.5 times the coal calory and in Germany still more.

In the plant constructed in accordance with the invention there is a heat consumption of only about 2550 calories, so that converted into terms of running costs the new method of driving is superior to the drive with Diesel engines which has hitherto been regarded as very favourable. This is of particular importance for all maritime countries which are dependent on coal bases, as for instance Germany and the by far greater part of Europe.

What I claim is:

A marine high pressure superheated steam power plant comprising a high pressure boiler, a heat exchanger, a multi-cylinder reciprocating engine divided into a high pressure part and a low pressure part, a pipe from the boiler to the heat exchanger, a pipe connecting the heat exchanger to the high pressure part of the engine,

a pipe supplying the exhaust steam from the high pressure part of the engine to the heat exchanger, a pipe for conducting exhaust steam from the exchanger to the low pressure part of the engine, a low pressure steam accumulator, auxiliary engines and cooking devices, a second pipe connecting the exchanger with the steam accumulator, means for supplying steam from the accumulator to the auxiliary engines, heating and. cooking devices, the heat exchanger being so dimensioned that with the temperature reduction of the live steam before entering the high pressure part of the engine, the volume of the exhaust steam is increased to such an extent WILHELM SALGE.

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