A, MVR process is introduced
1, the principle of MVR
MVR is steam mechanical compression technology, (mechanical vapor recompression). MVR evaporators is reused itself to produce secondary steam energy, so as to reduce the demand for the external energy of an energy saving technology.
MVR its working process is the low temperature steam by compressor compression, temperature, pressure, heat enthalpy increase, and then enter the condensing heat exchanger, in order to make full use of the latent heat of steam. In addition to the drive to start, the entire process of evaporation without raw steam out of the evaporator of secondary steam, the compressor compressed, pressure, temperature, enthalpy increase, and then sent to the heating chamber evaporator used as heating steam, keeping a material liquid boiling state, while heating steam is condensed into water. So it's fully use steam was to waste, recycling of latent heat, increase thermal efficiency, gave birth to the efficiency of steam is equivalent to 30 effect of multi-effect evaporation.
To make the evaporation device manufacturing as simple as possible and easy to operate, can be used with compressor and centrifugal compressor. These machines in 1:1. The 2 to 1:2 compression ratio within the scope of the volume flow rate is higher.
2, MVR process
System by a single effect or double-effect evaporator, compressor, vacuum pump, circulating pump, separator, operation platform, electrical instrumentation control cabinet, valves and piping system composition, simple structure, convenient operation and maintenance.
Second, the evaporator is introduced
1, MVR falling film evaporator
Working principle:
Materials to concentrate on the heat exchanger tube box to join, the distribution of material through the cloth liquid into each heat exchange tube, and along the wall to form homogeneous liquid membrane, heat exchange tube, tube liquid membrane in the process of downflow by shell side heating steam heating, and flows downward while boiling evaporation. To the bottom of the heat exchange tube material to concentrate and secondary steam.
Concentrate into the tube box, secondary steam into the gas-liquid separator. Secondary steam entrainment in the gas-liquid separator liquid droplets has been removed, the pure evaporation from the separator to the compressor. After compressor to compress the secondary steam as a heating steam heat source to the shell side of the heat exchanger used in evaporator. Continuous evaporation process.
Features:
1, high thermal efficiency
2, cover an area of an area small
3, material stay time is short, not easy to induce material deterioration.
4, suitable for high viscosity material.
Scope of application:
Falling film evaporator is suitable for the preconcentration process, MVR evaporation crystallization process can evaporate viscosity larger materials, especially suitable for heat-sensitive materials, but shall not apply to the treatment of crystalline materials.
2, MVR forced circulation evaporator
Working principle:
Forced circulation evaporator consists of evaporation separator, heat exchanger and forced circulation pump. The material within the heat exchange tube heat exchanger was outside the heat exchange tube steam heating temperature. Materials under the action of a circulating pump up to the evaporation separator, in evaporation separator due to the evaporation material static pressure drop in the material.
Evaporation to produce secondary steam overflows from the material, the material is concentrated supersaturation and crystal growth, remove supersaturated material into the forced circulation pump, in under the action of circulating pump into the heat exchanger, material cycling or evaporating concentration crystal.
Crystal slurry from the circulation line with discharge pump output. Evaporation separator in the upper part of the secondary steam after evaporation separator after the separation and purification defoaming device to the compressor, the compressor after the secondary steam compression to the shell side of the heat exchanger is used as the evaporator heating steam, realize continuous evaporation heat cycle.
Features:
1. Heat transfer coefficient is low;
2. The heat transfer surface is not easy to form scale or crystallization.
Scope of application:
Suitable for easy scaling, crystallization, evaporation and concentration or high viscosity material evaporation crystallization process.
3, OSLO MVR evaporation crystallizer
Working principle:
OSLO evaporation crystallizer consists of OSLO evaporator, heat exchanger and forced circulation pump. The material within the heat exchange tube heat exchanger was outside the heat exchange tube steam heating temperature. Materials under the action of a circulating pump up to the OSLO evaporation crystallizer, in OSLO evaporation crystallizer due to the evaporation material static pressure drop in the material.
Evaporation to produce secondary steam overflows from the material, the material being too full enrichment, supersaturated solution in the center of the OSLO evaporation crystallizer pipe solution was associated with a decrease in good contact with small crystals and make the crystallization of further growth, growing larger crystal after elution column elution to large crystal precipitation to the elution column under the slurry pump is used to thick. The crystallization of smaller in OSLO mould continue to grow.
After clarification of the liquid is forced circulation pump to the heat exchanger to heat, so the material cycle is evaporating crystallization or enrichment. OSLO evaporation crystallizer in the upper part of the secondary steam after separator after the separation and purification defoaming device to the compressor, the compressor after the secondary steam compression to the shell side of the heat exchanger is used as the evaporator heating steam. Implement continuous evaporation heat cycle.
Main features:
1) crystal granularity, granularity
2) equipment large volume, high cost
Scope of application:
Applies to crystalline grain size larger material production.
4, MVR evaporation DTB crystallizer
Working principle:
Type DTB crystallizer is a kind of typical crystal slurry circulation within the mold. Due to the diversion tube inside the mold set, formed the circulation channel, make the crystal slurry with good mixing conditions, can quickly eliminate in evaporation crystallization degree of supersaturation, can make the solution of saturation at relatively low levels.
Especially suitable for the solubility curve steep products better. Type DTB crystallizer performance is good, the production of high strength, a larger grain production particles, not easily and the crystallizer scarring. It has become one of the main form of continuous crystallizer.
Main features:
Production of high strength, crystalline grain is bigger, stable performance.
Scope of application:
Applicable to the crystalline grain size is larger, the production of high strength material production.
Third, technical summary
In general, the technical features of MVR evaporators are as follows:
(1) clean energy, high thermal efficiency, low power consumption, no pollution.
(2) industrial waste water "zero emissions" meet the national discharge standard.
(3) to be processed material to adapt to the range.
(4) integrated multiple effect, saving the manufacturing cost.
(5) the low temperature evaporation, evaporation temperature, non-standard, pressure vessel design basis).
(6) can be continuous and intermittent discharge.
(7) high degree of automation, low running cost.
(8) small volume and strong mobility.
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