JPH0478784A - Sea water leading device for tanker with horizontal bulkhead - Google Patents

Abstract

PURPOSE:To prevent cargo oil from flowing out in the case of a disaster at sea by slightly opening and closing a pressure relief valve according to a draftignition or the like to slightly reduce the pressure in an ullage space for pushing up the cargo oil higher than a broken port. CONSTITUTION:A pressure relief valve 1 is additively provided at the upper end of a cargo vent pipe 4 in a lower cargo oil tank 6. The relief pressure PO of the pressure relief valve 1 is set in conformity with the following formula (pa+gammaSWXd) - (Pr+gammaoilXhoil+gammaSWXhSW), here each signal expresses as follows: atmospheric pressure as Pa, specific gravity of sea water as gammaSW, draftignition as (d), pressure in an ullage space of a lower cargo oil tank 6 as Pr, specific gravity of cargo oil as gammaoil, thickness of cargo oil in the lower cargo oil tank 6 as hoil, and thickness of oily water layer led into the lower cargo oil tank 6 as hSW. The relief pressure Po is set in conformity with the above formula to prevent the cargo oil from outflow caused by outside sea water led through a broken port 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] Value - The present invention relates to a seawater introduction device for a tanker with horizontal bulkheads.

[Conventional technology]

In the case of conventional tankers without horizontal bulkheads, if the bottom of the tank ruptures due to grounding, etc., introducing seawater from the outside world into the tank will cause the hull to lose its posture, and there is a risk of sinking. It was not possible to provide an introduction device.

In addition, cargo oil tanks that have been damaged due to grounding, etc. - Even if the oil leakage temporarily stops, oil may leak out again when the ship is shaken or towed due to worsening weather. However, in tankers with horizontal bulkheads, In the event of a marine accident, if an appropriate amount of external seawater is allowed to flow into the lower cargo oil tank by slightly releasing the pressure in the ullage space with a pressure relief valve inserted into the cargo vent branch pipe, oil will not leak out again. It is thought that this can be prevented.

The Sho Tsuna Honten Sai was proposed in light of these circumstances, with a horizontal bulkhead that minimizes oil spillage from the breach, prevents marine pollution, and conserves resources in the event of a marine accident such as running aground. The purpose is to provide a seawater introduction structure for tankers.

, a pressure relief valve is attached to the upper end of the cargo vent pipe of the lower cargo oil tank, and the relief pressure Po of the pressure relief valve is expressed by the following relational expression: % formula %) (where P,...atmospheric pressure, γsv...・Specific gravity of seawater, d
・・Hydration, P, ・Pressure in the ullage space of the lower cargo oil tank, γ, ■・・Specific gravity of cargo oil, h. , 1...Thickness of cargo oil in the lower cargo oil tank, γsw...Specific gravity of seawater, hRw...
・Thickness of the seawater layer introduced into the lower cargo oil tank) is set to 100%, and is characterized by preventing cargo oil from flowing out by introducing external seawater.

[Function] According to IIry:, in the event of a marine accident, the pressure in the ullage space is slightly reduced by slightly opening and closing the pressure relief valve in accordance with the choking and the like.

Then, depending on the magnitude relationship between the pressure in the ullage space and the pressure of the external seawater, external seawater flows into the lower cargo oil tank through the breach, forming a layer of seawater at the bottom of the tank, which removes the cargo oil from the breach. can be pushed upwards.

〔Example〕

One embodiment of this invention will be explained with reference to the drawings. FIG. 1 is a nine-plane cross-sectional view of the hull.

During the voyage, the stop valve 3 is closed to prevent the pressure Pt in the ullage space in the lower cargo oil tank 6 from escaping to another location via the cargo vent main pipe 4.

If a hole 8 occurs in the lower cargo oil tank due to the ship being grounded, etc., if the pressure inside and outside the hole 8 is balanced, the cargo oil will not flow out. The state at this time is expressed by the following equation (1).

P d+ 7 *ilx h all+ γ s*
xh'sw=P, +γswxd-=-(1) Here, P7...pressure of the ullage space in the lower cargo oil tank 6, 1...specific gravity of cargo oil ha + +... lower cargo oil Thickness of cargo oil layer in tank 7
8w... Specific gravity of seawater h sw... Thickness P of the seawater layer introduced below the lower cargo oil tank,... Atmospheric pressure d... Water stuttering.

However, in tankers with horizontal bulkheads 10, Pt#P
,, γ. , 〈γ□, h. 5. 〈Because the inequality of d holds true, immediately after the hole 8 occurs (at this time, h , w = 0
), the value on the right side is larger than the value on the left side, so the thickness of the seawater layer 9 into which external seawater is introduced from the hole 8 into the lower cargo tank is h av that satisfies equation (2). , adjust the pressure relief set point Po of the pressure relief valve 1.

Po=(P, +7swXd) (P t+ 7 allX h=+++ 7 swX
hsv)...(2) In this way, if the pressure relief setting value Po of the pressure relief valve 1 is set, the seawater layer 9 is
Because it is formed with a thickness of sw, there is no risk of cargo oil leaking out from the hole 8 when the ship is shaken due to worsening weather conditions or being towed, and the ship will sink due to excessive seawater flowing in. There is no danger of doing so.

Invention [Effects of Our Plan] According to such a structure, it is possible to prevent oil from flowing out again from a damaged part due to a marine accident such as a grounding, and to minimize environmental damage caused by the accident.

At that time, the introduced seawater is held down to a certain height, so
If the ship sinks due to the inflow of seawater more than necessary, a pressure relief valve is attached to the upper end of the cargo vent pipe of the lower cargo oil tank, and the relief pressure Po of the pressure relief valve is calculated using the following relational formula (%) (%) However, P: atmospheric pressure, γsv: specific gravity of seawater, d
・・Droplets, 2 units・・Pressure in the lower cargo oil tank's array space, γ. ,... Specific gravity of cargo oil, h all... Thickness of cargo oil in the lower cargo oil tank, γsv... Specific gravity of seawater, h s
v...thickness of the seawater layer introduced into the lower cargo oil tank), and by introducing external seawater to prevent cargo oil from flowing out, even in the event of a marine accident such as a grounding, oil will not leak out from the breach. This minimizes leakage and is extremely beneficial for business.

[Brief explanation of drawings]

aJll Figure 1 is a cross-sectional view of a tanker with horizontal bulkheads showing one embodiment of this year's sparrow. 1...Pressure relief valve, 2...Cargo vent branch pipe, 3.
... Stop valve, 4. Cargo vent main pipe, 5. Upper cargo oil tank, 6. Lower cargo oil tank, 7P. Port last tank, 7S... Starboard ballast tank, 8 hole, 9.・
・Seawater layer, 10...Horizontal bulkhead, γ. 1. ...Specific gravity of cargo oil, γ, V...Specific gravity of seawater, d...Hot water, h e
l l...thickness of the cargo oil layer in the lower cargo oil tank 6, h
sv...Thickness of the seawater layer 9 introduced below into the lower cargo oil tank 6, Po...Pressure of the pressure relief valve 1 IJ I
J-f set value, P...atmospheric pressure, Pt...pressure of the array space in the lower cargo oil tank 6, agent Masafumi Tsukamoto, patent attorney

Claims (1)

[Claims] In a tanker with a horizontal bulkhead, a pressure relief valve is attached to the upper end of the cargo vent pipe of the lower cargo oil tank, and the relief pressure P_o of the pressure relief valve is expressed by the following relational expression: P_o=(P_a+r_s_w×d ) − (P_r+r_e_i_l×h_e_i_l+r_s_
w×h_s_w) (However, P_a...atmospheric pressure, r_s
＿w・・Specific gravity of seawater, d・・Swallow water, P_r・・Pressure of ullage space of lower cargo oil tank, r_e_i_l・・
Specific gravity of cargo oil, h_e_i_l...thickness of cargo oil in the lower cargo oil tank, r_s_w...specific gravity of seawater, h_s_w...thickness of the seawater layer introduced into the lower cargo oil tank), and external seawater. A seawater introduction device for a tanker with a horizontal bulkhead, which is characterized by the introduction of a horizontal bulkhead to prevent the outflow of cargo oil.