Start-up and shutdown method of water transport in ethylbenzene/styrene unit

Abstract

The present invention relates to an operation starting / operation closing method for ethyl benzene / styrene apparatus water combined transportation. According to the method, a dehydrogenation liquid oil-water separation tank water phase is conveyed to a condensate steam stripping tower and is treated, water supply is performed on an ethyl benzene rectification unit and a styrene rectification unit through temporary pipelines, an ethyl benzene / styrene apparatus operation-closing material enters the dehydrogenation liquid oil-water separation tank through a temporary pipeline so as to be subjected to oil-water separation, the water phase in the dehydrogenation liquid oil-water separation tank is treated by the condensate steam stripping tower and a condensate filter and then is supplied for the ethyl benzene rectification unit and the styrene rectification unit so as to be subjected to water combined transportation, the oil phase in the dehydrogenation liquid oil-water separation tank is conveyed to a crude styrene storage tank in the tank region so as to be recovered, the material in the crude styrene storage tank is adopted as the styrene rectification unit water combined transportation operation starting material during operation starting, and a temporary pipeline is adopted to convey the oil-water mixture on the top of an ethyl benzene recovery tower to the dehydrogenation liquid oil-water separation tank to carry out dewatering. According to the present invention, the ethyl benzene rectification unit directly adopts the wastewater in the crude styrene storage tank to operate, and gradual transition from the water operation to the material operation is achieved so as to avoid the polymerization problem caused by the instable initial-stage operation.

Description

Technical field [0001] The present invention relates to a technology in the field of chemical engineering for reducing the material discharge loss of start-up and shutdown of an ethylbenzene / styrene device and the environmental pollution caused by waste water discharge. Background technique [0002] At present, more than 90% of the production capacity of the styrene industry uses the process technology of ethylbenzene dehydrogenation to produce styrene. The process route: use ethylene, ethanol, catalytic dry gas and other chemical raw materials and benzene to form ethylbenzene through the alkylation reaction, and then undergo ethylbenzene rectification. The unit obtains high-purity ethylbenzene, which is supplied to the dehydrogenation unit to generate crude styrene by adiabatic dehydrogenation process, and the styrene product is obtained from the styrene rectification unit. The polymerization inhibitor DNBP used in the styrene production process is a highly toxic chemical. If it...

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Problems solved by technology

The polymerization inhibitor DNBP used in the production of styrene is a highly toxic chemical. If it is not properly controlled, it will seriously pollute the environment and cause great harm to the human body.

[0003] The traditional shutdown method of the styrene plant using ethylbenzene dehydrogenation technology: After the ethylbenzene replacement and material removal of each tower and equipment, like other chemical plants, the steam is used to cook the equipment, and the hydrocarbon materials remaining in the equipment pipeline After vaporization, the torch and the atmosphere are discharged, and the material loss is serious, causing great pollution to the environment

[0004] The cooking effect of equipment such as reflux tanks, filters, pumps and auxiliary pipelines in each tower cannot be guaranteed; materials at the low points of pipelines and equipment cannot be completely sealed and discharged, and manual on-site discharge operations are required. The risk is high and the health and safety of employees is huge.

[0005] Process wastewater generated by steam cooking equipment needs to be discharged during the shutdown process, which contains a large amount of organic matter, especially the distillation polymerization inhibitor DNBP is a highly toxic chemical, which can only be discharged together with steam condensate, which seriously pollutes the environment

[0006] All kinds of human production activities are causing more and more serious damage to the environment of the entire earth. Environmental protection has gradually attracted the attention of the whole society. How to protect the environment has put forward higher requirements for chemical companies. Unable to achieve environmental protection standards

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