WO2006092639A1

WO2006092639A1 - Bilge water evaporator system

Info

Publication number: WO2006092639A1
Application number: PCT/HR2005/000062
Authority: WO
Inventors: Damir Drezga
Original assignee: Damir Drezga
Priority date: 2005-03-04
Filing date: 2005-11-25
Publication date: 2006-09-08
Also published as: HRP20050218B1; HRP20050218A2

Abstract

The Bilge Water Evaporator System contains a stern bilge water well (1) and prow bilge water wells (2) which serve for collection of bilge water seeping from various parts of the ship's engine room. It also contains a bilge water tank (4) attached via a gate valve (5) to the stern bilge water well (1). By means of the valve (5) bilge water is discharged from the stern bilge water well (1) into the bilge water tank (4). Thereafter, by means of a steam bilge water evaporator (6), the medium of which is dry saturated steam (p = 7 bar; evaporation temp. = 1650C), heat is transferred to bilge water stored in the bilge water tank (4) and it evaporates through a vent on the deck.

Description

BILGE WATER EVAPORATOR SYSTEM 1. AREA OF APPLICATION

This Invention applies to the bilge water system on board merchant vessels. 2. TECHNICAL PROBLEM

On board merchant vessels, bilge water collected in bilge water wells or stored in a bilge water tank is discharged into the sea through a separator, which is precisely regulated by IMO regulations and guidelines. Such bilge water treatment using a separator is prohibited by IMO in ports, coastal areas, channels and specific sea routes, and that is the main disadvantage of the existing bilge water system.

3. STATE-OF-THE-ART

Bilge water is generated as a result of seepage from various tubing in the ship's engine room, discharge of working medium from other machines and equipment due to minor repairs or major overhaul, etc. It is 85% to 95% saltwater and 5% to 15% lubricant and fuel.

The existing bilge water system is so designed that bilge water is collected in wells, then pumped into a bilge water tank and stored there. The tank then contains about 85% saltwater and 15% diesel fuel, heavy oil and lubricant. Bilge water from the tank is taken to a separator from which one portion - and that is purified bilge water containing less than 15 ppm oil - is discharged into the sea, while the rest consisting of a fuel-oil mixture is conveyed to the fuel-oil sludge system to be burnt in the incinerator.

4. ESSENCE OF THE INVENTION The Invention is aimed to improve the bilge water system on board merchant vessels. The Bilge Water Evaporator System includes stern and prow bilge water wells for collection of bilge water from various parts of the ship's engine room. It also includes a bilge water tank attached via a gate valve to the stern bilge water tank. Bilge water is discharged by means of the valve from the bilge water well into the tank. After that, the bilge water evaporator, which uses dry saturated steam (p = 7 bar; evaporation temp. = 165°C), transfers heat to bilge water in the tank which in turn evaporates over a vent on the deck. The mixture of diesel fuel, heavy oil and lubricant cannot reach a temperature higher than 165°C, which is insufficient for evaporation, whereby a risk of air pollution and fire is eliminated. The problem of the mixture of diesel fuel, heavy oil and lubricant, which makes around 15% of the bilge water content, is dealt with in the already existing way: by conveyance to the sludge system and burning in the incinerator. Scale that may accumulate on the bottom of the bilge water tank is removed by boiling the tank bilge water in chemicals used for the purpose. BRIEF DESCRIPTION OF DRAWINGS

The Bilge Water Evaporator System is shown in the attached drawings as follows:

• Fig. 1 - Bilge Water Evaporator System

• Fig. 2 - principle of using the gate valve • Fig. 3 - operation of the bilge water evaporator

Main parts of the system are marked in the drawings with numbers and letters:

1. - stern bilge water well

2. - prow bilge water well 3. - bilge water pump

4. - bilge water tank

5. - gate valve

6. - bilge water evaporator

M - mixture of diesel fuel, heavy oil and lubricant (Uap 25O⁰C - 35O⁰C) V - saltwater

P - steam direction (into the air) (p»^'l bar; teva_P~100^oC)

K - condensate outlet direction (from the steam evaporator)

Z - dry saturated steam direction (to the steam evaporator) (p«7 bar tevap«165°C) DETAILED DESCRIPTION OF THE INVENTION

When the stern bilge water well (1) is full, some time is required for bilge water to sediment. Due to a difference in density, the mixture of diesel fuel (q=750 kg/m³), heavy oil (q=975 kg/m³) and lubricant (q=920 kg/m³), which makes about 15% of bilge water, will stay above saltwater (q=1025 kg/m³) which makes about 85% of bilge water. By opening the gate valve (5), bilge water from the well (1) passes to the tank (4). The dimensions of the well (1) and the tank (4) are such that only saltwater can enter the tank through the valve (5), whereas the mixture of diesel fuel, heavy oil and lubricant always remains in the stern bilge water well (1). By using the gate valve (5) between the stern bilge water well (1) and the bilge water tank (4) the operation of the bilge water pump (3) is reduced to the pumping of the prow bilge water wells (2) into the tank (4). The mentioned operating principle of the valve (5) is shown in Fig. 2. Saltwater which has been pumped via the valve (5) from the stern bilge water well (1) into the tank (4) is evaporated by means of the bilge water steam evaporator (6). The evaporator (6), mounted on the bottom of the tank (4), is using as medium dry saturated steam from the ship's steam system (p=7 bar, tevap=165°C). Dry saturated steam in the evaporator (6) wholly condenses and transfers heat to saltwater stored in the bilge water tank (4) which evaporates at ambient pressure. Steam thus generated leaves the tank (4) through a vent on the deck and out into the air. Fig. 3 illustrates the evaporator's operating principle. The use of the steam bilge water evaporator (6) makes the whole bilge water separator system redundant. In case of occurrence of a mixture of diesel fuel, heavy oil and lubricant on the surface of saltwater stored in the bilge water tank (4), the action of the steam bilge water evaporator will still be possible. Saltwater will evaporate on the surface of the steam evaporator (6), mounted on the bottom of the bilge water tank (4), and the formed steam bubbles will separate from the walls of the evaporator (6). Due to a difference in density, the steam bubbles (q=0.598 kg/m³) pass through saltwater (q=1025 kg/m³), then through the mixture of diesel fuel, heavy oil and lubricant (q=750-975 kg/m³) and finally through the vent into the air. As the evaporation temperature of the mixture of diesel fuel, heavy oil and lubricant ranges between 25O⁰C and 35O⁰C, no vapors of these can occur as long as dry saturated steam (p=7 bar, tevap=165°C) is used as working medium of the steam bilge water evaporator (6). The mixture of diesel fuel, heavy oil and lubricant can reach a maximum

95 temperature of 165⁰Q which is insufficient for evaporation, whereby a risk of air pollution and fire is eliminated. According to current IMO regulations, such bilge water treatment would be allowed at open sea, as well as in ports, coastal areas, channels and specific sea routes, which is the main advantage of the bilge water evaporator system over the existing bilge water system on board merchant

100 vessels.

Claims

PATENT CLAIM

The Bilge Water Evaporator System which contains a stern bilge water well (1), prow bilge water wells (2) and a bilge water tank (4), is characterized in that the stern bilge water well (1) is attached via a gate valve (5) to the bilge water tank (4) incorporating a steam bilge water evaporator (6) with which bilge water is heated to the evaporation temperature.