Jet Engine Based Mobile GDL—CO₂ for Water Surface Cleaning

Abstract

In the present part of the book the basic design concept of the mobile 100 KW jet engine based laser installation has been presented. The contamination of large water areas (oceans, seas, lakes, and rivers) with petroleum products as a result of accidents and industrial activity of the mankind is one of major problems of protections of environment. BP’s operation case in the Mexican gulf is the best example of men made natural disasters. Any other contaminant, how dangerous is, it can not be compared with petroleum of a basis of universal utilization, number of contamination sources and degree of effect on all components of environment. Through penetration of petroleum products into water, there are deep, frequently irreversible changes of its chemical physical and microbiological properties. The following methods of disposal of petroleum contaminations of water: mechanical, physical-chemical, chemical, biochemical are used nowadays. The mechanical methods are such: collecting of petroleum from a surface manually of with different installations. All these methods are effective during limited time (from several hours to several days) only—time period during which the thickness of a petroleum film is great enough. As for physical-chemical methods it is necessary to mention, first of all, application of various adsorbing materials (polyurethane foam, coal dust, sawdust etc.), however all these methods are labor-consuming and low efficient. Besides they require secondary reprocessing of adsorbents. Chemical methods—removal of petroleum with the help of chemical substances. The basic disadvantages of this method are high price and fact, that detergents frequently are more toxic for water microorganisms, than petroleum. At microbiological decomposition of petroleum, the bacteria will be utilized, for which the petroleum is a nutritious medium. However natural velocity of microbiological decomposition of petroleum is too small, and this process requires long time duration. Besides the biological activity of microorganisms strongly depends on the temperature of water. The laser method of cleaning of water surface from a thin petroleum film is one of physic-chemical methods. Sometime later after penetration into water, the petroleum spreads on a surface of a water and forms very thin film (thickness several microns). This film cannot be forced to burn, since because of a good thermal contact to a surface of water the film cannot be heated to temperature ensuring steady combustion. The principle idea of a laser method consists in following. The laser beam passes through a petroleum film a then is absorbed in thin layer of water. The water heats very up to the boiling temperature, and the forming vapor destroys a film, bursting it in small-sized fragments, which mixing up with the hot vapor, are decomposed quickly with formation of simple non-toxic substances. The main advantages of a laser method consist in following. (a) This method is “fast-response” one, since does not require any special preparation; in emergency situations the time from the moment of obtaining of the alarm signal to the beginning the laser installation operation is determined only by time necessary for arrival of the ship or the helicopter with the installation on board in given area; (b) the method is contactless, i.e., does not require realization of preparatory or other activities in the oil spillage. For realization of the proposed technology, it is possible to utilize different types of lasers, as continuous (up to 100 kW), and pulse periodic (100–150 ns pulses with pulse repetition rate from 30 kHz and above). The laser radiation intensity in that case should be about 100–1,000 times higher in comparison with CW regime of the same laser. Theoretical estimations and the experiments have shown, that as a result of a laser beam action on a surface of a water and land, covered with film of hydrocarbon contamination, following effects can be fixed. Evaporation and burning, and in a continuous mode the consumption of energy for one gram of vaporized liquid on the order of value surpasses energy necessary for heating up to boiling temperature and evaporation of a film, that is explained by a heat consumption for heating of water. In a pulse mode, the consumption of energy it is per unit of vaporized mass of a liquid (film) approximately in five times less, thus the process of film ignition start more easily. Knocking out the particles of polluting substance above a surface of water under action of pulse or powerful scanning laser radiation. The physical mechanism of this effect is explained by sharp evaporation (boiling-up) of a thin layer of water under a layer of polluting substance. This process takes place whereas hydrocarbon polluting thin film has an absorption coefficient less, than water. Knocked out particles of petroleum at a height up to 30 cm is possible. For this case, the energy consumption per unit mass of a raised liquid is sufficiently less than energy necessary for evaporation and ignition. Another mode of cleaning can be reached by ejection effect of laser radiation in combination with low pressure air flux traveling along with gas dynamic laser effect. The character of a task to be solved superimposes certain conditions on operating characteristics of the laser device concerning both parameters of laser source, and concerning auxiliary systems. Technological lasers of 10–15 kW power range, that widely are used in production, will have the output completely insufficient for liquidation of large scale contaminations presenting the greatest danger according to the above-stated estimations. Such lasers can be utilized, at the best, for improvement of a process engineering of cleaning under modeling conditions. Besides, the character of this task dictates impossibility or extreme undesirability of use of the stationary civil engineering service line(electric power network, water pipe, main gas line etc.), in view of the requirement of a high self-sufficiency and mobility. The power unit should not limit mobility and thus provide totally energy needed of all installation, the necessary reserve of expendables and fuel onboard a complex. A capability of a fast redeployment from one type of a vehicle on another is also desirable.