Liquid ring vacuum pumps used in coal industry of advantages

Liquid ring vacuum pumps are important equipment for safety production in coal industry, the main purpose of which is to pump gas in coal mine seam to make sure safety in mine. 2BE series vacuum pumps are core products of Jinggong, with the following advantages:

1. overall consideration to the design and configuration of vacuum system, improve its reliability.

2. adopt circulatory system to cut down water consumption.

3. belt driving or gear box driving is optional according to site condition.

4. Improved impeller structure to prevent scaling and foreign body deposits inside the pump.

5. Inspection hole design is convenient for check and maintenance.

6. suitable for gas mine of low breathability, long pipe connection, and asks for high capacity and vacuum.

7. Suitable for mine of low gas density or changeable density, especially adjacent seam with wide changeability.

Working process of gas pump

Coal seam are divided into high negative pressure zone and low negative pressure zone. High negative pressure zone refers to original coal seam, with ordinary negative pressure no less than 13KPa; low negative pressure zone refers to goaf area, the mined coal seam, whose return gas is no less than 4KPa. To pump gas in high negative pressure zone, many long holes are bored first in the coal seam, and then insert the steel pipe into the holes and leave connections outside holes, seal the steel pipes and gaps between pipe outer surface and holes to make sure no gas leaks from the gaps; cover the steel connections with hose which connected with main suction pipes to pump coal seam gas. During suction process, coal seam water, coal dusts and gas enter the main pipes, and coal dusts are removed by skimmer, water discharged by full auto drainer, gas enters liquid ring pumps via anti-backfire device, explosion prevention device and flowmeter, and then discharged into air by vacuum pumps or generated.

Cut-off water protector

Cut-off water protector is used for various water pumps which asks for mine anti-explosion safety and water supply detection. When pipes are in shortage of water, the protector detects and send orders, then the electrical contacts of relay jumps to cut off pump and motor; when water supply returns normal in the pipe, the electrical contacts of protector resume and allow switches on.

Orifice flowmeter

When fluid passes the throttling gear, local shrink is produced, flowrate increases, and the differential pressure is produced in two sides of downstream. With relevant known parameters, the relation between differential pressure and flowrate can be inferred according to flow continuity and Bernoulli equation, and then the flowrate is obtained.

In orifice plate installation the orifice is concentric with pipe, and its surface is vertical to pipe axis; small orifice is towards drill position and bell towards pump position.

Principle and application of three proofings

The three proofings are essential safeguarding devices in coal gas system, which is composed of anti-explosion, anti-backfire and anti-gas returning devices, usually they are installed on suction and discharge pipes of pumps. When suction pipe is on fire or explodes, the fire will be cut off by anti-backfire device and the blast breaks rubber plate (aluminium plate) to relief pressure; When discharge pipe is caught on fire and explodes, the fire and blast are also cut off or decompressed. Suction pipe can be closed by anti-gas returning device to prevent accident expanding.

Another function of anti-gas returning device is to pump water inside anti-gas returning device into suction pipes by negative pressure when pump stops running, if not discharged in time, the suction will be faced with resistance. Therefore reasonable use of three proofing device is vital important method to ensure safety operation of coal gas pumping system.

1. Positive and negative water drainer: its function is to discharge ponding water in suction and discharge pipes, with a floater inside, when enough water runs into the drainer, the float valve opens and back in place when water is discharged.

2. Proof board: it is positioned in water sealed explosion-proof vent. If pressure increases fast, proof board is first to burst due to its low hardness, this will free anti-explosion device and whole system from break down, and the proof board need to be renewed.

3. Six flame screens: they are designed in anti-backfire device to prevent hot gas sparking, and the outermost screen is made of stainless steel, this will effectively resist slag shock in pipes.

4. Slag baffle: it is in slag remover, and its function is to stop the pipe slags and stack in remover outlet. Slag pile can be cleaned by opening the remover’s valve when the pumps stops. It is only used in suction pipes.

5. Baffle in backwater prevention device and anti-gas returning device: its used to close pipes rapidly to stop gas and ponding water returning to mine. Besides, anti-explosion vent is positioned in the device to effectively avoid accident such as explosion.