Lately, increasing attention has been paid to the environment protection in navigation too. The International Maritime Organization (IMO) has determined a code of regulations which - presumably since 1998 - would be effective all over the world and would be extended to all ships (with the exception of specially indicated ones). In particular, maximum emission values for nitric oxides NO_x and sulphur oxides SO₂ were determined in the amendments to MARPOL Convention.

These circumstances stimulate innovation activity of many scientists and designers from many countries in the field of creating technologies which can - after J. Vollnweider’s apt expression - “mate economy and ecology”.

Major diesel-makers, such as Zulzer Brother Ltd and New Zulzer Ltd, Krupp Mark Maschinenbau GmbH, MAN B&W Diesel AG, and a number of others, have been carried out developments in the field of diminishing noxious matter emission in exhausts of marine power plants.

The following technological solutions in the field of diminishing ships’ diesel motors throw-outs are the main ones:

• adaptation of the motor construction, optimization of the fuel apparatus work;
• using SCR catalysts (selective neutralization);
• using water-and-fuel emulsions and water injection.

In the first case, due to improving the motor construction, magnitudes are reached which corresponds to maximum allowable concentration of noxious matters in exhausts. With taking into account that the established standards will become tougher, this way may hardly be considered as comprehensive. Changes in the fuel apparatus work can also help reach maximum concentrations, in particular, that of No_x, but increase in fuel expenditure may be the payment for that.

The use of SCR catalysts allows to diminish the NO_x emission in the air, but their high cost (according to J. Vollnweider, the cost may be equal to $100,000 per 1 mW of the station’s power) compels to search out an alternative to this technology.

The third direction, namely, the use of water-and-fuel emulsions or of water injection seems to be the most productive. The application of water-and-fuel emulsions is just what allows to successfully “mate economy and ecology”. According many sources, the fuel saving in their application can be up to 5 percent.

The vibrocavitation emulgator developed and patented within the framework of the project provides three-step fuel processing - mixing, dispersing and homogenization to drops size not more than 5 mkm. All these three phases are effected with one plant arranged in one unit and having a common drive.

One of the variants of emulgator with a productivity of 10 m³/hour is presented in figure 1. Table 1 contains some specifications of emulsions obtained with the help of such emulgators.

Table 1

In 1994, bench tests were conducted of water-and-fuel emulsion prepared with the use of the vibrocavitation technology. The tests were conducted in conformity with the Russian standard procedures and international regulations on a motor with the following parameters: n_n =1800 min^-1, Ne=18 kW, tests duration 200 hours.

Table 2

A partial disassembling of the motor after the tests showed lack of scale on the cylinder-and-piston group elements. The water-and-fuel emulsion had played a good “cleaning” role. There were no traces of water affecting the fuel fixtures and motor.

In both testing and subsequent research sedimentation and aggregation steady water-and-fuel emulsions were obtained which had no visual changes while being stored for a period of from two months to one year.

Subsequent running trials on the “Alexander Prokofiev” and “Evgeny Mravinsky” motor ships confirmed the results obtained before.

In all, with the help of the station, over 1200 tons of “naval” black oils were processed, whereas the main motors worked steadily. Control surveys conducted before and after the trials showed diminishing scale on piston heads, cleanness of the cylinder-and-piston group and of the scavenging windows.

At present, trials are being completed of the vibrocavitation technology as applicable to furnace black oils in boilers of thermo-electric power stations. Adding water in fuel leads to increasing ecological effect in relation to diminishing noxious throw-outs in the air: in CO - by 1.5-2 times, in NO_x - by 2-2.5 times.

Back