Catalogue of Safety Production Technology Equipment for Eliminating Backward Hazardous Chemicals (Second Batch)

  Rotary cutting machine is one of the main equipments for producing plywood. It is divided into card cutting machine and cardless rotary cutting machine. With the advancement of technology, digital control technology is also applied to the production of rotary cutting machine. CNC rotary cutting machine. The appearance of the CNC rotary cutting machine not only improves the quality and precision of the production veneers, but also greatly improves the production efficiency and the automation of the whole machine.

  CNC cardless rotary cutting machine is an important equipment in plywood production line or veneer production line. It is mainly used for the re-rotation of the remaining (or round) wood core with card shaft rotary cutting machine for secondary use, and the length of wood In the segment, the wood core in a certain diameter range is cut into veneers of different thicknesses, and the diameter of the rotary cutting is small.

  Features:

  1. Use servo motor to drive precision screw feed.

  2. It is only necessary to input the plate thickness number when replacing the plate thickness, no need to change the gear, and the cutting precision is high.

  3. Different wood species can also be cut together without affecting the thickness of the board.

  4. The surface finish is good, and it is not sensitive to the reaction of the yin and yang of the wood.

  5. Power saving, simple operation and convenient maintenance.

Recently, the Ministry of Emergency Management has formulated and released the "Catalogue of Safety Production Technology Equipment for Eliminating Backward Hazardous Chemicals (Second Batch)" (hereinafter referred to as the "Catalogue"). The interpretation of the relevant content is as follows:

1、 Background of the Development of the Catalogue

The Opinions on Comprehensively Strengthening the Safety Production of Hazardous Chemicals issued by the General Office of the Communist Party of China Central Committee and the General Office of the State Council propose to promote industrial structure adjustment, timely revise and publish the catalog of outdated safety technology processes and equipment, legally eliminate production capacity that does not meet national and industry standards for safety production, and effectively prevent and control risks. Article 38 of the Work Safety Law of the People's Republic of China clearly requires that the state implements an elimination system for processes and equipment that seriously endanger production safety, and production and business units shall not use processes and equipment that should be eliminated and endanger production safety.

To this end, in October 2020, the Ministry of Emergency Management issued the "Catalogue of Safety Production Technology Equipment for Eliminating Backward Hazardous Chemicals (First Batch)" (Emergency Department [2020] No. 38), promoting the elimination of a batch of backward safety production technology equipment for hazardous chemicals, effectively promoting enterprises to increase safety investment, accelerating the improvement of intrinsic safety level and safety guarantee capacity, and playing an important role in effectively preventing safety accidents in hazardous chemical production and promoting the stable improvement of the national chemical and hazardous chemical safety production situation.

However, in recent years, some typical accidents have occurred in enterprises related to nitrification process, hydrogen peroxide production, etc., causing significant casualties and property losses, deeply exposing that some enterprises still have low intrinsic safety levels and high safety risks in process technology and equipment facilities. Meanwhile, with the continuous research and application of new processes, technologies, and equipment in recent years, the industry has developed safer, more advanced, and reliable alternative process technologies or equipment, creating favorable conditions for further phasing out outdated process technology equipment.

In order to conscientiously implement the decisions and deployments of the Central Committee of the Communist Party of China and the State Council, deepen the implementation of the three-year action plan for tackling the root cause of chemical and hazardous chemical safety production, and continuously improve the essential safety level and safety guarantee capacity of chemical and hazardous chemical production and operation enterprises, the Ministry of Emergency Management has organized relevant industry associations, key enterprises, etc. to prepare a "Catalogue". The introduction of the Catalogue is a powerful means to promote the improvement of the intrinsic safety level of chemical enterprises. Through rigid constraints, it promotes enterprises that do not meet safety requirements to increase safety investment, fundamentally eliminate accident hazards, fundamentally solve problems, and further prevent and resolve major safety risks of hazardous chemicals.

2、 Main contents of the Catalogue

The Catalogue lists a total of 7 outdated process technology equipment, including 4 process technologies and 3 equipment and facilities. Each item specifies the scope of implementation, the time limit for elimination and transformation, and replacement suggestions.

Eliminating outdated process technologies includes: fixed bed hydrogen peroxide production process with acid-base alternation, designated as prohibited, requiring new (expanded) projects to be prohibited, and completing the renovation of existing projects within five years; The artificial scraping and unloading technology of organic silicon slurry and the open slurry hydrolysis technology are prohibited, and new (expanded) projects are required to be prohibited. The existing projects should be renovated within two years; The intermittent carbonization process for producing strontium carbonate and barium carbonate (using hydrogen sulfide wet gas holders) is prohibited and requires new (expanded) projects to be prohibited. The existing intermittent carbonization process for strontium carbonate is renovated within one year, and the existing intermittent carbonization process for barium carbonate is renovated within two years; Intermittent or semi intermittent kettle nitrification processes are classified as restricted and require the prohibition of 27 chemicals such as nitrobenzene. The transformation should be completed within two years.

Eliminating outdated equipment includes: internally injected thermal oil type electric heating reactors (oil bath reactors, oil bath pots) without cooling measures, which are classified as restricted and require reactors involving key hazardous chemical processes to be prohibited. In service equipment should be replaced within one year; The internal floating roof storage tanks of oil depots adopt shallow pan or open compartment internal floating roofs, which are classified as prohibited. Oil depots that require a hazardous chemical business license are prohibited, and the in-service equipment is renovated within two years; Single end mechanical seal centrifugal pumps and packing seal centrifugal pumps (excluding submerged pumps) are classified as prohibited, requiring Class A, extremely hazardous, highly hazardous, and hazardous chemicals with operating temperatures exceeding the self ignition point to be prohibited. In service equipment should be replaced within three years.

It should be noted that if the "elimination type" in the Catalogue is classified as "prohibited", new (expanded) construction projects will be strictly prohibited from the date of document publication; Existing projects or in-service equipment should be renovated or replaced within the transition period specified in the "restricted scope", and cannot continue to be used after the deadline. If the elimination type is a "restriction" category, it shall be executed according to the specific restriction scope of the relevant items. The new (expanded) construction projects in the Catalogue specifically refer to hazardous chemical construction projects that are submitted to relevant government departments for approval and filing after the date of document publication.

3、 Implementation of the Catalogue

This year marks the beginning of the three-year action plan to address the root cause of chemical and hazardous chemical safety production. The formulation and release of the Catalogue is an important measure in the three-year action plan. Each region should strengthen overall planning and organization, work together with the safety rectification of old chemical equipment and the automation transformation of high-risk process enterprises, and accelerate the implementation of the three-year action plan tasks to ensure high-quality development with high-level safety. Firstly, we need to strengthen publicity and guidance, promote through various means such as training lectures and media interpretations, create a good atmosphere, guide relevant enterprises to deeply understand the importance, and accelerate the implementation of outdated technology and equipment elimination and transformation and upgrading work. Secondly, relevant enterprises should be organized to conduct self-examination against the Catalogue, understand the basic number of outdated process technology and equipment, clarify the list of enterprises that need to be renovated, promote relevant enterprises to develop plans, increase safety investment, clarify the renovation time limit, and strive to make changes as much as possible and as quickly as possible to ensure that safety risks are controllable; Those who fail to implement elimination or renovation as required by the deadline shall be investigated and dealt with in accordance with the law. We need to organize experts to strengthen guidance and services, benchmark against international advanced technology levels, promote the high-quality completion of renovation tasks by enterprises through "one enterprise, one policy", and urge enterprises to do a good job in identifying and controlling safety risks during the renovation period to prevent accidents from occurring during the renovation process.

The Emergency Management Department has simultaneously prepared the definitions of the "Catalogue" clauses, listing the main considerations for each elimination item, highlighting safety risks or typical cases, and introducing the advantages of alternative process technology equipment, for relevant enterprises in various regions to better understand and master the relevant requirements in implementation.

Attachment:

Eliminating outdated hazardous chemical safety production

Interpretation of Articles in the Catalogue of Process Technology Equipment (Second Batch)

1、 Fixed bed hydrogen peroxide production process with acid-base alternation

Hydrogen peroxide (H2O2) aqueous solution usually decomposes slowly to produce water and oxygen, but its stability deteriorates under alkaline, heating, or impurity conditions, and the decomposition rate accelerates, even causing explosions. At present, some domestic enterprises adopt the fixed bed production process of acid-base alternation to produce hydrogen peroxide, which is recycled throughout the entire system and enters alkaline and acidic processes alternately. It is easy to cause hydrogen peroxide solution or working fluid containing hydrogen peroxide to come into contact with alkaline materials due to facility equipment failures or operational errors, resulting in rapid decomposition or even explosion of hydrogen peroxide, with high safety risks.

At present, the fluidized bed production process is one of the more advanced hydrogen peroxide production processes in the industry. The mass and heat transfer effects between the solid, liquid, and gas phases in the hydrogenation tower of this process have been enhanced, the hydrogenation reaction efficiency has been improved, and the by-products have been reduced. Therefore, this process does not require the regeneration of the working solution with alkaline solution, eliminating the possibility of decomposition explosion caused by contact between hydrogen peroxide solution and alkaline substances. Moreover, the fluidized bed production process has been completed and stably operated in China, effectively improving the intrinsic safety level and safety guarantee capability of the process, representing the direction of technological progress in the hydrogen peroxide industry. The fully acidic fixed bed production process eliminates the alkaline washing process in the main circulation process of the working fluid and sets up an independent working fluid treatment system. The working fluid can only be returned to the system after being analyzed to be neutral or weakly acidic. For some enterprises that do not have the conditions to implement fluidized bed production process transformation, they can choose to replace it with the fully acidic fixed bed production process.

2、 Artificial scraping and unloading technology of organic silicon slurry and open slurry hydrolysis technology

Organosilicon slurry residue refers to some high boiling dark oil-like solid-liquid mixtures produced during the synthesis of chlorosilane monomers, with complex compositions and generally containing small amounts of carbon powder, silicon powder, copper catalysts, etc. Due to the difficulty in cleaning areas such as adhering to the vessel wall, some companies use manual scraping and unloading.

During the process of manual slagging and unloading, chlorosilane in organic silicon slurry will react with moisture in the air to form corrosive hydrochloric acid mist, and the slurry may self ignite when exposed to air. In the process of slurry hydrolysis treatment, the slurry reacts with alkaline water to release hydrogen chloride gas and hydrogen gas. Using open slurry hydrolysis technology, the hydrogen chloride gas will form corrosive hydrochloric acid mist in the air; Hydrogen gas is prone to accumulate and cause fires and explosions, posing high safety risks.

The use of organic silicon slurry automatic closed discharge technology and closed slurry hydrolysis technology can effectively collect the hydrogen chloride gas and hydrogen released during the discharge and hydrolysis reaction process, prevent harmful gases from escaping during manual slag removal and discharge from causing harm to human health, and effectively avoid fire and explosion accidents caused by disorderly discharge of harmful gases. The continuous operation rotary kiln slurry incineration technology is also an advanced organic silicon slurry treatment process, which can use high temperature to harmless treat organic silicon slurry. The substances in the slurry are oxidized and pyrolyzed at high temperature, with a high removal rate.

3、 Intermittent carbonization method for producing strontium carbonate and barium carbonate (using hydrogen sulfide wet gas holders)

At present, domestic production enterprises such as strontium carbonate and barium carbonate mostly use intermittent carbonization production process. This process involves introducing a strontium sulfide (SrS) solution into a carbonization tower and reacting with the introduced carbon dioxide gas in an intermittent manner to obtain a strontium carbonate (SrCO3) slurry, which generates tail gas containing hydrogen sulfide (H2S) and is processed by the Claus hydrogen sulfide tail gas treatment system to produce sulfur. Due to intermittent production, the concentration and flow rate of by-product hydrogen sulfide tail gas fluctuate greatly. Generally, a hydrogen sulfide gas cabinet needs to be installed between the carbonization tower and the sulfur recovery unit to provide a stable hydrogen sulfide gas source for the subsequent Claus hydrogen sulfide tail gas treatment system. Due to hydrogen sulfide being a highly toxic gas and a binary weak acid, storing hydrogen sulfide in a wet gas holder can easily cause corrosion and jamming of the gas holder, and sealing failure can easily lead to hydrogen sulfide leakage and poisoning accidents.

At present, the most advanced technology is to use the continuous carbonization process of strontium carbonate and barium carbonate or the multi tower carbonization production process, accompanied by a continuous treatment system for hydrogen sulfide tail gas, without the need for a gas holder to temporarily store hydrogen sulfide, significantly reducing the safety risk of hydrogen sulfide leakage and poisoning accidents caused by wet gas holder storage of hydrogen sulfide.

4、 Intermittent or semi intermittent kettle nitrification process

Nitrification reactions usually belong to strong exothermic reactions, and the raw materials, intermediate products, by-products, and their products used have explosive hazards; Intermittent or semi intermittent kettle nitrification production processes have low levels of mechanization and automation, with a large number of on-site operators. Once the reaction is out of control, it is easy to cause explosion accidents, resulting in mass casualties and high safety risks. In recent years, some enterprises have transformed the nitrification reaction process from traditional intermittent/semi intermittent kettle production processes to microchannel, tubular reactors, or continuous kettle nitrification production processes. This not only achieves continuous and stable operation of the process, but also eliminates the need for manual operations such as unloading and cleaning, effectively reducing the safety risk of mass casualties among on-site operators. Compared with traditional kettle reactors, microchannel and tubular reactors have outstanding advantages such as high mass and heat transfer efficiency, short reaction residence time, and fewer hazardous materials. The widespread promotion and application can significantly reduce safety risks and improve the intrinsic safety level of nitrification reaction processes.

5、 Internal injection thermal oil type electric heating reaction kettle without cooling measures (oil bath reaction kettle, oil bath kettle)

The reactor body of the electric heating reactor with internal thermal oil injection is a double-layer structure, and an electric heating rod is set inside the interlayer. Before use, the thermal oil needs to be manually injected into the jacket. During operation, the electric heating rod converts electrical energy into heat energy, achieving the purpose of heating the materials inside the reactor. For thermal oil type electric heating reaction vessels with cooling measures, when the temperature of the reaction vessel is too high, the supporting cooling measures can be used to implement rapid cooling of the reaction vessel while cutting off the electric heating power supply, thereby avoiding accidents caused by temperature loss of the reaction vessel. However, for internally injected thermal oil type electric heating reaction vessels (oil bath reaction vessels, oil bath vessels) without cooling measures, natural cooling and cooling can only be achieved by cutting off the power supply. Once the reaction vessel exceeds the temperature, it is prone to reaction runaway, leading to fire and explosion accidents.

6、 The internal floating roof storage tank of the oil depot adopts a shallow pan or open compartment type internal floating roof

Internal floating roof storage tanks mainly store Class A, B, and A liquids, which pose a high risk of fire. The vast majority of tank fire accidents that have occurred over the years involve such liquid storage tanks. A shallow plate type inner floating roof is an inner floating roof that has no compartments, pontoons, or other floats, and is directly in contact with liquid through a bowl shaped floating roof. The open compartment type inner floating roof is a circular open compartment set around the floating roof, with only a single layer of plate in the middle. These two types of floating discs have poor stability. Once the floating disc corrodes and penetrates, it can cause flooding and sinking of the floating disc, leading to direct exposure of flammable and explosive materials to the atmospheric environment, which can easily cause fire and explosion accidents. As alternative equipment, the steel internal floating roof and the assembled stainless steel fully connected liquid internal floating roof have good stability and a low probability of catching fire on the entire cross-sectional area of the storage tank. In addition, the assembled stainless steel fully connected liquid internal floating roof has a small gas phase space, which can effectively reduce the volatilization of oil in the storage tank and has high safety and reliability.

7、 Single end mechanical seal centrifugal pump and packing seal centrifugal pump (excluding submerged pumps)

The common types of centrifugal pump shaft seals include packing seals, single end mechanical seals, double end mechanical seals, series mechanical seals, dry gas seals, and other sealing types. Single end mechanical seals and packing seals have relatively low reliability and are prone to leakage due to seal failure, resulting in fire, explosion, and poisoning accidents.

The double end mechanical seal has two end face seals. The buffer solution (or nitrogen) in the sealing chamber is pressurized. If the first stage seal fails, the buffer solution leaks from the sealing chamber into the conveying medium, and the conveying medium does not leak out. A series mechanical seal consists of two or more sets of single end face seals arranged in the same direction in series, equipped with an external sealing liquid supply system, and the buffer liquid in the sealing chamber is not pressurized. The inner seal is the main seal, equivalent to a built-in single end face seal, and the sealing chamber is filled with liquid from the sealing tank. The outer seal can prevent the isolation liquid from leaking into the atmosphere. Dry gas seal is a series mechanical seal that uses nitrogen as the buffer medium. Nitrogen is introduced into the sealing chamber to ensure that the main seal has a certain back pressure, which can greatly extend the service life of the main seal; The process medium leaked from the main seal is discharged into the torch with the sealing gas to ensure that the process medium does not leak into the atmosphere. Shielded pumps, magnetic pumps, diaphragm pumps, and other leak free pumps have also been widely promoted and applied. Due to their unique structural design, these types of leak free pumps achieve complete physical isolation between the materials transported inside the pump and the environment, fundamentally avoiding the possibility of leakage caused by seal failure in traditional centrifugal pumps, resulting in a higher level of intrinsic safety. Therefore, for Class A, extremely hazardous, highly hazardous, and hazardous chemicals with operating temperatures exceeding the self ignition point, the use of double end mechanical seals, series mechanical seals, dry gas sealed centrifugal pumps, or leak free pumps such as shielded pumps, magnetic pumps, and diaphragm pumps has higher reliability and better applicability.

Editor: Tan Zailong