GB/T 35802-2018Production technical regulation for sodium carbonate (English PDF)

3.1 Sodium carbonate producer enterprise

An enterprise that produces sodium carbonate by using a raw salt as a raw material, a method of producing a sodium carbonate by a combined alkali method (Hou's alkali method), an ammonia-base method (Solvay method), and a trona processing method A company that produces sodium carbonate.

3.2 Combined soda process (Hou's alkali method)

A method for producing sodium carbonate and producing ammonium chloride in parallel by using ammonia, carbon dioxide and raw salt produced by an ammonia plant as raw materials.

3.3 Ammonia-soda process (Solvay process)

A method for producing sodium carbonate using raw salt and limestone as main raw materials and ammonia as an intermediate auxiliary material.

3.4 Trona processing method

A process for producing sodium carbonate by evaporation or carbonation using trona as a raw material.

3.5 Production process control

Production process control is to ensure that the production process is under control, production, installation and service that directly or indirectly affect product quality. The analysis, diagnosis and monitoring of the operating techniques and production processes taken by Cheng.

4.1 Device size

The scale of sodium carbonate production facilities for new construction, reconstruction and expansion shall comply with the access regulations of the sodium carbonate industry.

4.2 Process

4.2.1 Ammonia alkali method

The ammonia-alkali process should include. brine refining, limestone calcination, brine ammonia, ammonia brine carbonation, filtration, distillation, compression, heavy alkali Calcination, heavy ash process system.

4.2.2 Combined alkali method

The combined alkali process should include. raw salt refining, ammonium chloride crystallization, wet ammonium drying, ice machine refrigeration, ammonia absorption, ammonia mother liquor II carbonation (its Including decarbonization process and shift gas process), heavy alkali filtration, heavy alkali calcination, carbon dioxide compression system.

4.2.3 Natural alkali processing method

The trona processing method includes a sesquiline process and a carbonation process, and the sesquiline process and the carbonation process should include.

a) The sesquiline process should include evaporation crystallization, filtration, centrifugation, light ash calcination, and light ash hydration process systems.

b) The carbonation process should include a carbonation, wet decomposition, compression, filtration, calcination process system.

5.1 Site selection and general layout

5.1.1 Site selection

5.1.1.1 The location of the enterprise shall be based on China's current laws, regulations, standards for environmental protection, safety production and environmental protection, and the proposed construction project. Hygienic characteristics of the production process and its environmental requirements, occupational hazards, combined with the current situation of the construction site and the local government The overall planning, as well as hydrological, geological, meteorological and other factors, are determined by comprehensive analysis.

5.1.1.2 The location of the enterprise should avoid the natural foci; for the reasons that cannot be avoided due to the needs of the construction project, etc., the specific epidemic situation should be designed. Preventive and control measures.

5.1.1.3 The location of the enterprise should avoid places and facilities that may cause or exist health hazards, such as landfills, sewage treatment plants, and gas transmission. Pipes, and areas where water and soil may have been contaminated by the original industrial enterprises; if construction projects are needed but difficult to avoid, they should be sanitized first. Evaluate the assessment and take the necessary control measures based on the assessment results. The design unit shall clearly require the construction unit and the construction unit to formulate the construction period. Interim emergency rescue plan for public health emergencies after operation and operation.

5.1.1.4 The enterprise shall be located on the upwind side of the protected object in the local summer minimum frequency wind direction, and shall comply with the national protection distance specified by the state. Request to avoid interaction with surrounding areas. For the current national health protection distance requirements, it is advisable to have a health impact Evaluate and make a judgment based on the actual evaluation results.

5.1.1.5 When enterprises with different sanitary characteristics are arranged in the same area within the joint venture, it is advisable to avoid cross-contamination and joints caused by different harmful factors. Cooperation.

5.1.1.6 In addition to meeting the above requirements, the company's site selection should also comply with the relevant provisions of GB 50489 and GB 50187.

5.1.2 General layout

5.1.2.1 The general layout of the plant area should be clearly defined as functional zones, which can be divided into production zones, non-production zones and auxiliary production zones. Its engineering land should be based on Hygienic requirements, combined with the rational layout of the nature, scale, production process, transportation, natural conditions of the site, technical and economic conditions of industrial enterprises.

5.1.2.2 The general layout of the enterprise, including the current status of the building (structure), the proposed building location, roads, sanitary protection, greening, etc. GB 50016, GB 50489, GB 50187, GBZ 1 and other national standards.

5.1.2.3 The principle of zoning of the functional plane division of the enterprise plant area should be followed. the construction of the phased construction project should be an overall plan, so that each single building is It is orderly and reasonable in its functional area, avoiding the destruction of the original functional division when the construction is completed; the administrative office should be set in the non-production area; the production workshop And the auxiliary buildings related to production shall be arranged in the production area; the buildings (parts) that generate harmful substances and the environmental quality requirements are higher or Buildings (parts) with higher cleanliness requirements should be properly spaced or separated.

5.1.2.4 The toxic and harmful production workshops where acute occupational hazards may occur should be matched with the corresponding accident prevention and emergency rescue. Equipment, facilities, and emergency access.

5.1.2.5 The calcination process should be close to the carbonation process to make the transport route of heavy alkali short and convenient. The distance from the calcination process to the packaging plant is not It should be too far away, and the layout of the packaging plant should be convenient for loading and transporting.

5.1.2.6 The location of the compression process should consider that the furnace gas pipeline of the calciner (including the lime kiln gas pipeline of the ammonia plant) should not be too long, and to the carbon Acidified lines should also be shorter.

5.1.2.7 The location of the thermal power station (boiler room) should be close to the steam center to avoid the steam line being too long. At the same time, the thermal power station (or the total plant pressure reduction station) The cable direction to each power distribution room should be reasonable, and the cable length should be short.

5.1.2.8 The lime process of the ammonia-alkali production enterprise should be considered in addition to the transportation of limestone and coke, and the lime milk to the distillation process and kiln gas. The length of the line to the compression process should be short. When using solid salt as raw material, in order to reduce solid transportation, the salting process should be set in the nearby salt field or In the salt storage area of the plant, it is convenient to send the saturated brine to the brine refining process after salting.

5.1.2.9 The salt washing process of the joint alkali production enterprise should be arranged close to the salt storage yard to facilitate the transportation of salt. At the same time, salt washing (or salt) should be considered. The distance to the salting-out crystallizer should be close to the external cooler of the ammonium chloride process to reduce the cold loss.

5.1.2.10 The general layout of the joint alkali production enterprise shall be fully considered in addition to the respective requirements of the ammonia plant and the alkali plant. The close relationship between the two devices to shorten the pipeline and facilitate production.

5.2 Vertical arrangement

5.2.1 A single-storey building should be used in a plant that disperses large amounts of heat or harmful gases. Discharge heat and harmful gases when the plant is a multi-storey building The production process should be arranged at the upper level of the building. If it is necessary to be placed in the lower layer, effective measures should be taken to prevent contamination of the upper working environment.

5.2.2 Production equipment with large noise and vibration should be installed in a single-storey building. When designing needs to place these production equipment in a multi-story plant When it is in the room, it should be installed on the ground floor and take effective sound insulation and vibration reduction measures.

5.2.3 All types of pipes containing volatile gases and vapours should not be empty from the instrument control room and the auxiliary room where workers often stay or pass. Neutral and underground passage; if it is required to pass, it should be tightly sealed, and should have anti-pressure, corrosion resistance and other properties to prevent harmful gases or vapors from escaping to indoor.

5.3 Plant design

5.3.1 The orientation of the building shall be such that there is good natural ventilation and natural lighting in the room. The spacing between two adjacent buildings is generally not less than two. The height of the taller building.

5.3.2 For workshops with natural ventilation, the design of the skylights in the workshop should meet the hygiene requirements. the drag coefficient is small, the ventilation is large, and it is easy to open and adapt. For different seasons, the area of the sunroof vent should be slightly larger than the sum of the inlet window and the inlet dam. The hot processing plant should be equipped with a skylight block Wind plate, the lower edge of the side window of the factory building should not be higher than 1.2m from the ground.

5.3.3 High temperature, hot processing, buildings with special requirements and more personnel should avoid the sun. Shading and rain protection should be provided above the side windows of the factory building. Fixed plate (shed), avoid direct sunlight, convenient for ventilation in rainy days.

5.3.4 The noise reduction and vibration of the plant design and equipment layout should adopt noise reduction and vibration reduction measures.

5.3.5 The workshop office should be close to the factory layout, but it should not be adjacent to the place where dangerous and toxic substances are handled. Should meet the lighting, lighting, pass Wind, sound insulation and other requirements.

5.3.6 The structure of the building with corrosive environment shall comply with the requirements of GB 50046.

5.4 Process Design

5.4.1 Labor safety and health protection facilities, environmental protection facilities and fire protection facilities shall be designed, constructed and constructed simultaneously with the main project. Put into production.

5.4.2 Process design should optimize the process flow, rationally optimize equipment configuration, and fully consider safety facilities, environmental protection facilities and fire protection facilities and processes. Combination of devices.

5.4.3 Process design should adopt advanced technology and equipment to automate the production process. DCS centralized control system should be adopted. Ammonia base, joint Alkali production enterprises should be equipped with fully functional automatic control systems, strict process and equipment management according to the technological characteristics of the enterprise. Heavy use The number of hazardous chemicals that are regulated by the point constitutes a major hazard source for production and storage. It should be equipped with an automatic control system to achieve temperature and pressure. Real-time monitoring of important parameters such as force and liquid level.

5.4.4 Production process equipment of the same nature shall be arranged in a centralized manner, and full consideration shall be given to the spacing requirements of operation, overhaul, and safety passages.

5.5 Building (construction)

5.5.1 The building (construction) of the plant shall comply with the relevant requirements of safety and health, fire protection, local earthquake level, etc., and have sufficient height and surface to be used. It is good for ventilation.

5.5.2 Effective anti-corrosion measures shall be taken for the ground, walls, beams and columns of the building (construction) such as production plants.

5.5.3 The floor of the production workshop should be flat, easy to clean, clear and diverted.

5.5.4 The safety requirements of fixed steel ladders and platforms shall comply with the provisions of GB 4053.1, GB 4053.2 and GB 4053.3.

6.1 Ammonia alkali method

6.1.1 Process Overview

Raw salt and limestone are used as raw materials, ammonia is used as intermediate medium, refined by brine, limestone calcination, ammonia absorption by refined brine, carbonation of ammonia brine, Light alkali sodium carbonate is produced by heavy alkali filtration, mother liquor distillation, heavy alkali calcination and gas compression; part of the light sodium carbonate is cooled and sent After the finished product is packaged, another part is further processed to produce heavy sodium carbonate which is cooled and sent to the finished package.

6.1.2 Brine refining process

6.1.2.1 Process tasks

The raw salt was dissolved in water to prepare a saturated crude brine. By purifying the crude brine, it is prepared to meet the requirements of the ammonia absorption process and the carbonization process. Refined brine, brine refining process is mainly to remove calcium, magnesium ions and water insolubles in salt water, including the following.

a) Reducing the clogging of pipes and towers during ammonia aspiration, prolonging the service life and increasing the production capacity of equipment. In crude brine Calcium and magnesium can react with ammonia and carbon dioxide in the process of ammonia absorption to form a single or double salt of calcium or magnesium to precipitate the pipeline and the tower. Blockage, shortening the service life of equipment pipes and significantly reducing equipment production capacity;

b) Improve the quality of sodium carbonate. As the crude brine absorbs ammonia and carbonizes, calcium and magnesium precipitates are precipitated in the product, resulting in sodium carbonate. Increased water insoluble content, affecting product quality;

c) Reduce ammonia and salt losses during production. If the brine is not refined, the rate of crusting will increase when ammonia is sucked, and the tower and pipeline will be cleaned. The number increases, frequent start-stop switching, resulting in the loss of ammonia and salt water, increasing the consumption of salt and ammonia.

6.1.2.2 Process method

6.1.2.2.1 Lime-ammonium carbonate method

The lime-ammonium carbonate method removes the magnesium and calcium impurities contained in the brine in two steps.

a) adding lime milk to the reactor to convert the divalent magnesium ions into magnesium hydroxide precipitates, which will sink in a brine clarification tank. The precipitate settles and separates. The reaction equation is.

Mg2+ + Ca(OH)2 -> Mg(OH)2 (precipitate) + Ca2+

b) introducing carbonized tail gas (containing ammonia and carbon dioxide) into the calcium removal tower to convert the divalent calcium ions in the primary brine into calcium carbonate sinking It was precipitated and removed (sedimented in a secondary brine clarification tank to separate). The reaction equation is.

Ca2+ + 2NH3 + CO2 + H2O -> CaCO3 (precipitate) + 2NH4+

6.1.2.2.2 Lime-sodium carbonate method

First, the lime milk and sodium carbonate are mixed in a certain ratio (calcium calcium and magnesium content according to the crude salt water) to eliminate sodium bicarbonate in the lye, which will be the most The final active ingredient is a mixture of sodium hydroxide and sodium carbonate (also called caustic solution) sent to the brine reactor to cause the calcium and magnesium ions in the crude brine to sink simultaneously. Dock down. The reaction equation is.

NaHCO3 + Ca(OH)2 = NaOH + CaCO3 (precipitate) + H2O

The calcium and magnesium ion reaction formula is.

Mg2+ + 2OH- -> Mg(OH)2 (precipitate)

Ca2+ + CO3 2- -> CaCO3 (precipitate)

6.1.2.3 Process flow

6.1.2.3.1 Lime-ammonium carbonate method

The raw salt is metered and sent to the upper part of the salt drum, and is in countercurrent contact with the light brine (fine water) entering at the bottom to make a nearly saturated crude brine.

The crude brine is self-flowing or pumped into the mixing tank, and an appropriate amount of secondary mud (preservative) and lime milk are added, and the mixture is thoroughly mixed and thoroughly added.

The amount of flocculant (polyacrylamide), after mixing evenly, flows into a brine clarification tank for clarification.

The supernatant (primary brine) from the upper part of the brine clarification tank is pumped to the top of the calcium removal tower of the calcium removal tower (the calcium tower is divided into two sections, the upper part is The net ammonia section and the lower part are calcium removal sections) to absorb ammonia and carbon dioxide from the carbonation tail gas coming from the bottom of the calcium removal tower to carry out a calcium removal reaction.

The liquid coming out from the bottom of the calcium removal tower (tower halogen) flows into the secondary brine clarification tank for clarification. Clarified barrel upper by secondary brine The clear liquid (secondary brine or refined brine) is pumped to the ammonia absorption system for ammonia absorption.

In addition to the calcium section of the calcium tower, the gas exits into the upper part of the net ammonia section, and the ammonia remaining in the tail gas is washed with low-temperature water containing no ammonia. Net ammonia The water flows into the mud washing tank by mixing with the seawater and the primary mud.

The secondary mud discharged from the bottom of the secondary brine clarification tank is pumped to the mixing tank as a primary salt clarification aid for the recovery of secondary salts.

Ammonia in cement. The primary salt cement discharged from the bottom of the brine clarification tank enters the mixing tank and is mixed with the effluent and seawater of the net ammonia removal section.

Feeding) is pumped to the center barrel of the mud drum. The washing water washes the lower layer of the mud bucket into the washing mud bucket and washes it in countercurrent contact with the mixture, and the light salt after washing The water (fine water) overflows from the upper layer to the water bucket, and is sent to the salt slurry by the mixed water pump. The waste sludge discharged from the bottom of the mud bucket is pumped to the purification process. […]