Supply a complete set of second-hand double effect falling film evaporators/The abbreviation for mechanical vapor compression technology. MVR is an energy-saving technology that utilizes the energy generated by its own secondary steam to reduce the demand for external energy. As early as the 1960s, Germany and France had successfully applied this technology to fields such as chemical engineering, food, papermaking, pharmaceuticals, seawater desalination, and wastewater treatment. The working process of the evaporator is to compress the low-temperature steam through the compressor, increase the temperature and pressure, increase the enthalpy, and then enter the heat exchanger for condensation.

Process Introduction

The solution is circulated in a falling film evaporator through a material circulation pump in the heating tube. The initial steam is heated by fresh steam outside the tube, which heats and boils the solution to produce secondary steam. The generated secondary steam is drawn in by a turbocharged fan, and after pressurization, the temperature of the secondary steam is reduced

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As the temperature increases, it enters the heating chamber as a heating source for circulating evaporation. After normal start-up, the turbo compressor sucks in secondary steam, which is then pressurized and converted into heated steam, thus undergoing cyclic evaporation.

The evaporated water eventually becomes condensed water and is discharged during the multi effect evaporation process. The secondary steam of one effect of the evaporator cannot be directly used as the heat source of the main effect, but can only be used as the heat source of the secondary effect or several secondary effects.

As a heat source for this effect, additional energy must be provided to increase its temperature (pressure). The steam jet pump can only compress a portion of the secondary steam, while the MVR evaporator can compress all the secondary steam in the evaporator

The secondary steam coming out of the evaporator is compressed by the compressor, with an increase in pressure, temperature, and enthalpy, and then sent to the heating chamber of the evaporator as heating steam to maintain the boiling state of the feed liquid, while the heating steam itself condenses into water.

In this way, the steam that was originally intended to be discarded is fully utilized, latent heat is recovered, and thermal efficiency is improved. The economic efficiency of steam production is equivalent to 30 effects of multi effect evaporation. To make the manufacturing of the evaporation device as simple and easy to operate as possible, single effect centrifugal compressors are often used, which can also be high-pressure fans or turbine compressors.

These machines have a higher volumetric flow rate within the compression ratio range of 1:1.2 to 1:2. For low evaporation rates, piston compressors, slide compressors, or screw compressors can also be used. The evaporation equipment is compact, occupies a small area, and requires minimal space.

It can also eliminate the need for a cooling system. For existing factories that require expansion of evaporation equipment but lack steam and water supply capacity, as well as insufficient space, especially in situations where low-temperature evaporation requires condensation of chilled water, both investment savings and good energy-saving effects can be achieved.

Principle of recompression

Due to cost reasons, single-stage centrifugal compressors and high-pressure fans are commonly used in mechanical steam recompression systems. Therefore, the following explanation is for this type of design. A centrifugal compressor is a volume control machine, which means that regardless of the suction pressure, the volume flow rate remains almost constant. The change in mass flow rate is proportional to the suction pressure.

Design and Functionality/Supply a complete set of second-hand double effect falling film evaporators

Machines used for gas compression operate according to the principles of positive displacement or dynamics. In a positive displacement machine, the moving parts of the machine separate the suction chamber from the pressure chamber, reducing the volume of the operating chamber while increasing the gas pressure. In the case of using a reciprocating compressor, this process is achieved through the movement of the piston inside the cylinder. In a powered machine, gas energy is supplied through the high-speed rotation of the impeller blades. The gas is first accelerated and then decelerated through a diffuser located downstream of the impeller. In this way, high speed is converted into pressure energy. According to the direction of fluid passing through the impeller, the relevant equipment is called axial flow, mixed flow, or centrifugal compressor. The type of compressor depends on the operating conditions of the relevant application. The key parameters are the required pressure rise and the flow rate of the compressed steam. π is the ratio of the final pressure p2 to the suction pressure p1, defined as the compression ratio. Due to the fact that evaporation devices often operate within a vacuum range, with moderate heating surface loads and small temperature differences, centrifugal compressors are usually used.