Process Introduction

Mixing nitric acid and circulating acid in proportion to form a uniform mixture containing about 5% nitric acid and about 68% sulfuric acid. The mixed acid is pumped to the tubular reactor, and with benzene (about 10% excess of benzene to avoid the formation of dinitrobenzene and ensure high yield of nitrobenzene) is subjected to continuous nitration to form nitrobenzene, the residence time is about 12 minutes; The water produced by the nitration reaction dilutes the sulfuric acid from 68% to about 65%, and the heat generated by the reaction raises the reaction temperature from about 95 ° C to about 130 ° C.

The reaction mixture containing the organic matter and sulfuric acid from the reactor enters the gravity separator. The organics and spent sulfuric acid are separated here. The hot nitrobenzene containing a small amount of excess benzene and traces of sulfuric acid is heat-exchanged with the feed benzene and sent to the washing equipment for further processing. The spent sulfuric acid containing traces of organic matter and nitric acid is sent to a concentration process for disposal. The spent sulfuric acid from the nitrification process is flashed in the flasher, and some of the water is distilled off to concentrate the sulfuric acid concentration from 65% to 68%. The reaction heat absorbed by sulfuric acid during evaporation is self-evaporating, which accounts for about 85% of the heat required for flash vaporization, and the insufficient portion is supplied from the outside. The concentrated sulfuric acid is overflowed from the flasher into the storage tank, and then pumped to the nitrification process for recycling, and the lost small amount of sulfuric acid is supplemented here.

The flashed gas is indirectly cooled by circulating cooling water. The gas containing traces of benzene, nitrobenzene and nitrogen oxides that has not been condensed is sucked out by a vacuum system and sent to an exhaust gas treatment unit. The condensed liquid flows to the separator where the organic phase is separated from the aqueous phase. The organic phase containing nitrobenzene and benzene is sent to a washing apparatus and the crude nitrobenzene to be further treated, and the aqueous phase containing traces of acid and organic matter is washed with crude nitrobenzene. The crude nitrobenzene is subjected to a three-stage neutralization countercurrent washing with the aqueous phase of the concentration step to remove dinitrobenzene and nitrophenol. After three stages of washing, the nitrobenzene is washed with water to neutrality. Neutral nitrobenzene is sent to the next step for purification. The two washing wastewaters are stripped of nitrobenzene by steam stripping, pyrolyzed and sent to a sewage treatment device, and the separated organic phase is returned to the washing process. Neutral crude nitrobenzene is preheated by preheater and sent to the distillation tower. After the material in the tower is heated by the reboiler, the benzene and water are distilled off from the top of the tower, and after being condensed by the condenser, the benzene water separator is separated and separated. The upper layer of benzene flows into the benzene storage tank, and the lower layer of water is removed from the trap after being treated by the wastewater tower. The refined nitrobenzene from the bottom of the column is exchanged with the crude nitrobenzene entering the tower, cooled by circulating cooling water, and collected in a storage tank.

Plate Heat Exchanger in the Process

Acid nitrobenzene heat exchanger: The inlet temperature is 120 ° C, the benzene is heated to 90 ° from normal temperature, and mixed with acid to prepare nitrobenzene. (Nitrobenzene: light yellow transparent oily liquid, relative water density: 1.205)

Condenser: Cooling with circulating cooling water. The medium is a gas from a flash tank containing benzene, nitrobenzene, nitrogen oxides, etc., and condensed into a liquid.

Tag:Plate and Frame Heat Exchanger

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    Liaoning Victory Industry Co.,Limited is a leading manufacturer in the heat exchanger industry with over 15 years of experience and specialize in heat exchanger & spare parts. We produce replaced plates and gaskets for Alfa Laval, APV ,GEA, Sondex , Vicarb ,Tranter, API/Schimidt Bretten, Hisaka, Funke, Thermowave,VIEX and etc.

    Our parent company Dayuanplate own one plate heat exchanger manufacturing base, one plate heat exchanger sealing gasket factory, one boiler factory and a R&D center.

    Dayuanplate is a technology R&D type enterprise, We developed three different series products can meet demands for different industries.

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    Just like a car or a computer, a heat exchanger needs regular maintenance to keep running at peak performance. Fortunately, PHE’s are generally easier to maintain than other types of heat exchangers, and problems tend to be easier to diagnose.

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    While less likely, other parts of a PHE can fail as well. It’s important to visually inspect the gaskets, frame and bars whenever you open up the heat exchanger for any kind of maintenance. A habit of cursory visual examinations can save a lot of time and money in the long run.

  • Exclusive Distributor of VHX in European Market

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    Because the heat exchanger plate works for a long time, the surface of the heat transfer plate will produce different degrees of dirt or deposits, thereby increasing the flow resistance and reducing the heat transfer performance. These are mainly the pressure difference between the inlet and outlet pressure gauges and the temperature of the cold medium outlet. Reduced, so we have to clean it, we need to debug the experiment after the cleaning is completed to ensure the normal use of the product, then what are the things we need to pay attention to during the debugging process?
    1. Reserve a certain inspection site around the location of the flat plate heat exchanger.
    2. Before installing the apv plate heat exchanger, clean the pipeline connected to it to prevent sand, oil, welding slag and other debris from entering the plate heat exchanger, causing obstruction of the flow channel or damage to the plate.
    3. When the plate heat exchanger is stopped and stopped in sequence, first close the high-pressure side medium solenoid valve, and then close the low-pressure side medium solenoid valve. When starting up, first open the low-pressure side medium plunger valve, and then open the high-pressure side medium plunger valve slowly after the medium fills the plate heat exchanger channel.
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    If there is a large amount of muddy sand or debris in the medium, the supporting decontaminator produced by Weike should be placed in front of the plate heat exchanger. The gasket heat exchanger has a low fouling coefficient, and the fluid violently rolls between the plates to form a turbulent flow. The excellent plate design avoids the existence of a dead zone, so that impurities are not easily deposited and blocked in the channel, and a good heat exchange effect is ensured.
    The above is all the things we need to pay attention to during the debugging process after cleaning. We only know these things to ensure the product usage rate.
    Weike is a manufacturer of environmentally friendly plate heat exchangers. We believe that the company's technical design capabilities, manufacturing capabilities, enterprise scale and after-sales service will win your trust.
  • Congratuation to VHX's Exhibited ISK-SODEX ISTANBUL 2019

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    ISK-SODEX exhibition is the third largest heating and cooling equipment exhibition in the world. This year it was hold in ISTANBUL TURKEY.

    In order to serve the market better and make follow-up visit to our local customers in Turkish market, we attended the ISK-SODEX ISTANBUL 2019. During the fair, we received about 100 companies who are in the heat exchanger industry and have have interest in related products. All of our local business partners spoke highly of the product and service we provided. We have made a very impressive promotion about our ability to supply good quality product and quick service hope we will get more and more inquiries through this event and welcome all interested customers visit our company.

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    Our main products are plate heat exchanger and spare parts for PHE maintenance, such as 100% replacement heat exchanger plate and plate heat exchanger gasket, we have more than 200 models available to fulfill different kinds of needs for plate heat exchangers.