Scribd
Upload
56 views46 pages

Pumping Cargo

Important

Uploaded by

romanpolyakov23047
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
56 views46 pages

Pumping Cargo

Important

Uploaded by

romanpolyakov23047
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
You are on page 1/ 46
PUMPING CARGO I GENERAL TYPE VESSEL A Manual from TEACH TECH MANILA, INC. to be used with the Training Video PUMPING CARGO IL Especially produced for WALLEM SHIPMANAGEMENT LTD. HONG KONG PUMPING CARGO I Our ship has reached the port where she should discharge her cargo of crude oil. To discharge the cargo the ship has four centrifugal Cargo Pumps. The Pumps are located to the bottom of the Pumproom The Pumproom is situated between the Engineroom arid the Cargo TankArea CARGO & BALLAST TANK AREA Let's take a closer look at the Pumproom and the Cargo Pumps. We will not discuss in what order the Tanks should be discharged or the Crude Oil Washing operation which is an integrated part of the discharge. Each Cargo Pump has a capacity of 4.000 m’/h. In front of the Pump is a Mudbox with a Strainer to protect the Pump from solids. On the pressure side pipe of the Pump is a Non Retum Valve and a Discharge Valve In this vessel these pipes are drawn back through the tanks to Cargo Tank 6 where they are drawn up to acting as both Risers and Drop Lines. This is what happens when the Pump is running. The so called Impeller is driven at high speed showering liquid through the Pump. The liquid is entering the rotating Impeller through the Eye in the middle. The Impeller Vanes force the liquid to the periphery of the Pump Velocity is converted to pressure in the casing of the Pump. Some important principles: Let's start with an empty shore tank, an empiy line and a ship's tank filled with 20 mof fresh water. Just for the discussion lc's imagine the Pump as a closed valve. Note the different heights marked. We «ise freshwater to simplify calculations using the metric system. w SHORE TANK SHIP TANK Let's put in some Manometers. One at the suction side and one at the Pressure Side of the Pump. Finally we put a Manometer where the ship is connected to the shore installation, at the ship's Manifold. 40m SHIP TANK We are now filling the lines with water. The Manometer at the Suction Side reads 2 kg/cm’, Pressure Side 6 and the Manifold Manometer 3,5 kg/om?. In the following we will reter to kg/cm? simply as kilos(kg) 60m. D «CHARGE HEAD TOTAL HEAD=40m_| | ie You can see the situation like this. There is one Column of Liquid - 20 m high — the SUCTION HEAD — standing on the Suction Side and there is an other Column — 60 m high - the DISCHARGE HEAD — standing on the Pressure Side of the Pump. The difference — 40 m —is the TOTAL HEAD. The Pump must create a bigger HEAD to transport the liquid from ship to the shore tani. Lets fill an additional 3 m water in the shore tank. You should note that the pressure at the Suction Side of the Pump rises with 3 kg. The pressure has nothing to do with the volume of the pipe or the tank. — Only difference in height counts. 43m SHIP TANK Another 3 mis added to the DISCHARGE HEAD. There is no change of the SUCTION HEAD. The TOTAL HEAD is now 43 m. This is the static situation. Let's run the Pump. We will use this symbol for the ENERGY added to the system by the Pump. c It also contains the RESISTANCE and nolo in pipes and valves. Pipes and valves SHIP TANK This is the ¢ynamic situation. Watch the changed readings of the Manometers as the Pump adds energy to make the water flow to the tank The energy added to the system is 5.5 Kg. — All Manometers in the system should show 5.5 Kg more if there was no Resistance. The Resistance results in a Pressure Drop in the lines: That's why the Manometer at the Manifold doesn't reeds 3.8 + 5.5 = 9.3 kg. The Resistance in the pipe eats 0.2 kg and the Manometer reeds 9.1. There is also a pressure drop on the Suetion Side of the Pump because of Resistance The Manometer there reads less then 2.0 kgif.8) Back to the running Pump. You can see it like there is a column of 18 m liquid standing on the Suction Side. And there is a column of 118 m standing on the Pressure Side. The DIFFERENCE between the two Manometers - 10.0 kg — converted into a column of fresh water is 100 m. The HEAD is 100 m. Always calculate the HEAD from the difference between pressures of the Pressure Side and the Suction Side, but remember that if the Suction Side Manometer shows under 0, you have to ADD the two readings to get the HEAD. UNSTABLE AREA ie H~@ 10 160 ~! 0% om § 140 30% remy 2 \o Sah ~ 100 a i] 70% rpm az 80 = 60 60% rpm. UNSTABLE AREA | 50% rpm

You might also like