Loading And Unloading Compressor

Our Chinese manufacturing facility is excited to showcase its innovative collection of oil-free lubricating compressors, engineered for superior efficiency and durability. These units are notable for their low operational speeds, sturdy construction, and dependable functionality, which guarantee a longer lifespan and straightforward maintenance. The ZW series distinguishes itself with a cohesive design, combining the compressor with key elements such as a gas-liquid separator, a filter, a dual-position four-way valve, a safety valve, a check valve, an explosion-proof motor, and a robust chassis. The result is a streamlined, lightweight unit that operates with minimal noise, robust sealing, ease of installation, and user-friendly operation.

The "Unloading Compressor" stands as an advanced industrial solution, meticulously designed to bolster both its efficiency and user-friendliness. Key aspects of this product include:

Rapid Unloading System: This compressor incorporates an advanced mechanism for swiftly and effectively decompressing and discharging gases or air, streamlining the unloading process.

Sturdy Construction: Utilizing materials of the highest caliber, its build quality ensures outstanding durability, capable of enduring the demanding conditions of industrial use.

Superior Performance: Engineered to excel, the compressor provides top-notch performance in compressing and releasing air, meeting the needs of a plethora of industrial tasks.

Energy Conservation: With its low energy consumption, the compressor not only lowers operational expenses but also supports sustainable environmental practices.

Minimal Upkeep: Thanks to its intelligent design and robust build, it demands low maintenance, thus maximizing reliability and minimizing the likelihood of operational interruptions.

Adaptable Applications: Engineered for versatility, it's a perfect fit across various sectors, ranging from industrial manufacturing to heavy-duty construction environments.

Enhanced Safety: The compressor comes fully equipped with safety valves and additional precautions to guarantee secure operations and mitigate the risk of accidents or equipment harm.

Sound Dampening Technology: It operates quietly, reducing auditory disturbances and making it an ideal choice for operations in areas where noise levels are a concern.

The product is engineered to excel in the swift and efficient handling of gases and liquids, excelling in tasks such as unloading, loading, emptying storage tanks, and recovering residual gases and liquids from substances such as LPG/C4, propylene, and liquid ammonia. It is widely employed in a range of industries, including the gas, chemical, and energy sectors, where it plays a vital role as an indispensable asset. With its adaptability and effectiveness, this product stands as a fundamental device for the manipulation and treatment of gases and liquids in these important industrial arenas.

Note:

It's important to understand that during the unloading operation, the compressor functions by increasing the pressure of the gas contained within the storage tank, which then propels it through the gas phase pipeline into the tanker. Simultaneously, the liquid is moved from the tanker back to the storage tank by leveraging the pressure difference created in the gas phase as a driving force, seamlessly executing the unloading procedure.

A noteworthy point is that pressurizing the gas phase inherently raises the gas's temperature. Yet, in this specific process, there is no requirement for artificial cooling. Introducing forced cooling after compressing the gas phase could potentially introduce complications or reduce the system's efficiency. The compressor's design, along with the system's unloading methodology, is finely tuned to manage temperature variations intrinsically, negating the need for extra cooling interventions. This design consideration helps maintain an efficient and hassle-free unloading process.

The unloading volume is calculated based on inlet pressure 1.0MPa, exhaust pressure 1.6MPa, inlet temperature 40°C, and liquefied gas liquid density 582.5kg/m3. When the working conditions change, the unloading volume will change accordingly, for reference only.

• Suction pressure: ≤1.6MPa

• Exhaust pressure: ≤2.4MPa

• Maximum pressure difference: 0.8MPa

• Maximum instantaneous pressure ratio: ≤4

• Cooling method: air cooling

  
  

The system's unloading capabilities are calibrated under distinct parameters: an inlet pressure set at 1.6MPa, an exhaust pressure at 2.4MPa, an inlet temperature established at 40°C, and a liquid propylene density marked at 614kg/m3. It is crucial to acknowledge that the unloading performance can fluctuate with any alterations in these operational conditions. As a result, the specified capacity should be regarded as a benchmark and might require revisions to align with the real-world operating environment.

• Suction pressure: ≤1.6MPa

• Exhaust pressure: ≤2.4MPa

• Maximum pressure difference: 0.8MPa

• Maximum instantaneous pressure ratio: ≤4

• Cooling method: air cooling

The unloading capacity of this system is quantified under certain conditions: with an inlet pressure at 1.6MPa, an exhaust pressure of 2.4MPa, an inlet temperature of 40°C, and a specified liquid ammonia density of 729kg/m3. It's essential to recognize that this capacity is variable and subject to adjustment depending on deviations from these specified working conditions. Consequently, the capacity figures presented should serve as an initial reference and might require modification to accurately reflect the conditions encountered during actual operation.

Schematic Diagram Of Unloading Process

When initiating the transfer of liquid, the conduit for the liquid phase that links the tanker with the storage tank is first opened. If the level of liquid within the tanker is above the level in the storage tank, gravity will facilitate the flow of liquid downwards into the storage tank naturally. This gravity-induced flow persists until the liquid levels balance out, at which point the flow naturally stops.

If, however, the liquid in the tanker is at a lower level than that in the storage tank, the compressor is promptly engaged. Positioning the four-way valve appropriately, the compressor draws gas out of the storage tank, increases its pressure, and then directs it into the tanker. This process amplifies the pressure inside the tanker while simultaneously diminishing the pressure within the storage tank. The resulting pressure difference then propels the liquid from the tanker into the storage tank.

Residual Liquid Recovery

In the process of recapturing the leftover liquid, the method is essentially the converse of the delivery process. Following the conclusion of the liquid transfer, the four-way valve gets toggled to its opposite setting, and the segmented pipeline shown in the schematic is sealed. With this configuration, the compressor takes in the remnant gas within the tanker, increases its pressure, and subsequently transfers it to the storage tank. This is carried out until the pressure of the leftover gas diminishes to a point where it is no longer practical to recover it.

During this recovery stage, it is imperative to keep a vigilant watch on the compressor's pressure ratio and the temperature at which the gas is expelled to ensure that these metrics stay within their designated safe and efficient operating thresholds. This vigilant monitoring is vital to uphold the system's integrity and to mitigate the risk of any possible hazards during operation.

Four-Way Valve Working Principle

To manipulate the four-way valve, one must pull its handle to alter its alignment. As depicted in Figure a, the valve aligns the A end for the incoming air. In this arrangement, the path of the gas commences at A, proceeds to B, and passes through an interconnected sequence of elements: the connection pipe, the intake filter, into the intake pipe of the compressor, through the compressor's mechanism, out via the compressor's exhaust pipe, and finally moves from the D end to the C end, with C acting as the point of exit for the gas.

Alternatively, when the four-way valve is adjusted to position B, as illustrated in the corresponding figure, the intake is redirected to the C terminal. Subsequently, the direction of gas flow is inverted, tracing from the C terminal back to the B terminal, traversing the same series of components in reverse order: it moves through the connecting pipe, the intake filter, enters the compressor's intake pipe, goes through the compressor, and exits via the compressor's exhaust pipe. However, in this orientation, the gas flows from the D terminal towards the A terminal, with the A terminal now functioning as the outlet for the exhaust. This setup enables the system to be operated and controlled with flexibility, adjusting the direction of gas flow as needed.

Example Guide for Selecting and Calculating the Appropriate Liquid Ammonia Unloading Compressor

一、Compressor inlet and outlet pressure selection

The saturated vapor pressure of liquid ammonia at 20~36°C

When operating in high-temperature conditions, where the saturated vapor pressure of liquid ammonia is elevated, a compressor model with an intake pressure of 16 and an exhaust pressure of 24 is chosen to adequately suit the demands of the high-temperature environment.

Note: The pressure unit is kg/cm2

二、Compressor Displacement Calculation

The calculation of the specific flow rate is more complicated, and it needs to be finally determined according to the calculation formula and experience. Only a simple calculation method is introduced here.

1. Calculate the volume of the tank car

According to the provided working conditions, first determine the total volume flow required to unload 15 tons of liquid ammonia tanker in one hour.

The specific gravity of liquid ammonia is 0.618, so the volume of 15 tons of liquid ammonia is: 15 ÷ 0.618 = 24.272m3; and since the tank truck is not allowed to be filled up, it is generally filled to about 80% of the volume of the tank truck, then the tank truck The volume is 24.272+15×0.2=27.272, so the volume of the tank car should be 30m3.

1. Calculate displacement

In order to transfer the liquefied ammonia from the tanker to the storage tank using the compressor, it is essential to first create a pressure differential between the two vessels. It usually takes around 15 minutes to establish the necessary pressure difference for the unloading process to commence. Given this setup phase, the actual time available for unloading the liquefied ammonia is reduced to about 45 minutes. To calculate the necessary volumetric flow rate for the unloading procedure within this time frame, you would take the total volume of 30 cubic meters (m³) and divide it by the 45-minute unloading time window, resulting in a required flow rate of 0.66667 m³/min (cubic meters per minute).

The process of compressing gas from 16 kg to 24 kg results in a reduction of the gas volume to about 0.66667 of its initial volume. This ratio is derived from the initial pressure of 16 kg being divided by the final pressure of 24 kg. Therefore, when calculating the required compressor displacement under these conditions, we divide the predetermined volumetric flow rate of 0.66667 m³/min by the volume reduction factor of 0.66667. The outcome of this equation is 1 cubic meter per minute (1 m³/min). This calculation confirms that the compressor capacity should be adequate to facilitate an efficient unloading process within the specified timeframe, taking into account the pressure increase from 16 kg to 24 kg.

According to the above calculation, the compressor model is selected as ZW-1.1/16-24