Energy-saving isothermal transformation process

Abstract

An energy-saving isothermal transformation process relates to the technical field of isothermal transformation, and comprises the following steps: treating saturated coal gas, introducing the treated saturated coal gas into a first-stage transformation isothermal reactor, and carrying out first-stage transformation reaction to generate first-stage transformed gas; performing heat exchange on the first-stage shift gas through a second steam mixer, introducing the first-stage shift gas into a second-stage shift isothermal reactor, and performing second-stage shift reaction to generate second-stage shift gas; carrying out waste heat recovery on the secondary shift gas; the secondary shift gas subjected to waste heat recovery enters the next process after being further cooled by circulating water, waste heat of the shift gas is recovered through cascade heat exchange, shift reaction heat is recovered to the maximum extent, circulating water consumption and process condensate discharge are reduced, and the energy-saving effect is remarkable.

Description

Technical Field

[0001] The invention belongs to the technical field of isothermal transformation, and in particular relates to an energy-saving isothermal transformation process. Background Art

[0002] In coal chemical plants, it is necessary to convert raw synthesis gas (containing , , The process gas composition required by the downstream device processing is obtained through the carbon monoxide shift reaction. The main chemical reaction equation is as follows: + → + , which is an exothermic reaction. In traditional industrial production, most fixed bed reactors are used, with high operating temperatures. Usually, the hot spot temperature of the catalyst bed is as high as 430°C, and temperature separation is prone to occur during the start-up process, resulting in a shortened catalyst life. In addition, due to chemical equilibrium limitations, the conversion rate of a single device is not high.

[0003] In recent years, the research on isothermal reactors has become a hot topic and has been gradually promoted and applied in industry. However, most of the public reports and materials only focus on the reactor itself, and there are few reports and studies on the reactor, steam drum and related control systems.

[0004] In the prior art, the circulating gas needs to be cooled and separated from the water during the circulation process, and the steam energy utilization rate in the process is low. DETAILED DESCRIPTION

[0005] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0006] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0007] This embodiment provides an energy-saving isothermal transformation process, comprising the following steps: The saturated coal gas is treated and introduced into a primary shift isothermal reactor for primary shift reaction to generate primary shift gas; The primary shifted gas is passed through a second steam mixer for heat exchange and then introduced into a secondary shift isothermal reactor for secondary shift reaction to generate secondary shifted gas; The waste heat of the secondary conversion gas is recovered; the secondary conversion gas after waste heat recovery is further cooled by circulating water and enters the next process.

[0008] It should be noted that: after the saturated coal gas is treated, it enters the primary shift isothermal reactor, and under the action of the catalyst, the primary shift reaction and Convert to and , and produce primary saturated steam as a by-product.

[0009] The catalyst is a catalyst. In the actual production process, the catalyst can be replaced according to the components of the upstream gas. The first-stage shift isothermal reactor and the second-stage shift isothermal reactor have the same structure and are only used as shift isothermal reactions at different levels. Saturated coal gas refers to coal gas with saturated water vapor. In this state, if the temperature drops or the pressure rises, the excess water vapor will condense into water droplets.

[0010] The first-stage conversion gas after the reaction in the first-stage conversion isothermal reactor is surrounded by a pipe network or array to perform heat exchange treatment on the treated saturated coal gas at the inlet of the first-stage conversion isothermal reactor.

[0011] After the heat exchange treatment, the primary conversion gas enters the secondary conversion isothermal reactor for secondary conversion reaction to generate secondary conversion gas, and secondary saturated steam is produced as a by-product. The secondary conversion gas generated from the secondary conversion isothermal reactor is at a high temperature. The reaction in the secondary conversion isothermal reactor is the same as that in the primary conversion isothermal reactor, and the main chemical reaction equations are as follows: + → + .

[0012] The secondary shift gas in a high-temperature state is recycled through the boiler feed water heater and the process condensate heater for waste heat recovery, and the condensate is separated through the separator, and then the heat is recovered in stages. The heat is recovered through the soft water heater, and the waste heat is recovered from the shift gas of the desalted water heater, which is further cooled by circulating water before entering the next process. The waste heat of the shift gas is recovered through cascade heat exchange, and the heat of the shift reaction is recovered to the greatest extent, which reduces the consumption of circulating water and the discharge of process condensate, and has a significant energy-saving effect.

[0013] In a further implementation manner of this embodiment, the saturated coal gas is separated from impurities doped in the saturated coal gas by a separator to obtain pre-purified saturated coal gas.

[0014] It should be noted that the specific steps of the separator for separating saturated coal gas are: When coal gas containing solid particles or liquid droplets passes through the separator, the heavier particles or liquid droplets will gradually sink due to gravity and separate from the gas. The centrifugal force generated by high-speed rotation will move the denser particles or liquid droplets to the outside, thereby separating them from the gas flowing in the center. By setting a filter or other types of filter materials, the gas can pass through while blocking the larger particles or liquid droplets, thereby achieving separation.

[0015] The separator can effectively remove harmful substances from saturated gas, significantly improving the cleanliness and quality of the gas. Clean gas can also reduce corrosion and wear on equipment such as pipelines, valves, and burners, thereby extending the service life of the equipment.

[0016] At the same time, clean gas can burn more efficiently, improve energy utilization, and reduce maintenance costs and downtime.

[0017] In a further implementation of this embodiment, the pre-purified saturated coal gas is preheated by the high-temperature shifted gas at the outlet position of the first isothermal converter to obtain the preheated saturated coal gas.

[0018] It should be noted that preheating of coal gas helps to improve the efficiency of subsequent chemical reactions and product quality.

[0019] According to Le Chatelier's principle, increasing the temperature can cause the endothermic reaction to move in the positive direction and generate more products. Preheating can evaporate the moisture in the coal gas and prevent the moisture from causing adverse effects in subsequent processes.

[0020] In the prior art, a separate preheater is mostly used to preheat the coal gas, and this method has a low utilization rate of waste heat in the process.

[0021] In this embodiment, the primary conversion gas in a high temperature state from the primary conversion isothermal reactor is placed in front of the gas inlet of the primary conversion isothermal reactor through a pipeline network to preheat the coal gas, thereby making full use of the waste heat in the process and greatly reducing the energy consumption in the overall process.

[0022] In a further implementation manner of this embodiment, the preheated saturated coal gas is humidified and temperature-controlled by a first steam mixer to obtain humidified and temperature-controlled saturated coal gas.

[0023] It should be noted that the humidification and temperature control of coal gas has a significant impact on the subsequent chemical reactions and production processes. By rationally controlling the humidity and temperature of coal gas, the reaction conditions can be optimized, and the product quality and production efficiency can be improved. Specifically: Humidification of coal gas can adjust reaction conditions. Many chemical reactions require specific humidity conditions to proceed efficiently.

[0024] Humidification can adjust the water vapor content in the coal gas to achieve the best reaction conditions; it can protect the catalyst. Some catalysts have specific requirements for humidity. Appropriate humidity can maintain the activity of the catalyst and prevent the catalyst from deactivation or coking.

[0025] Temperature control of coal gas can optimize the reaction temperature. Many chemical reactions are most effective at specific temperatures. Temperature control can ensure that the reaction is carried out within the most suitable temperature range, thereby improving the reaction rate and selectivity.

[0026] It can prevent coking and carbon deposition. Excessively high temperature may cause organic matter in the coal gas to coke or deposit, affecting the normal operation of the equipment. Proper temperature control can avoid these problems.

[0027] It can save energy and reduce consumption. Reasonable temperature control can reduce energy consumption and improve the energy efficiency of the entire system.

[0028] It should be noted that during the humidification and temperature control process, the amount of water vapor added needs to be precisely controlled to avoid excessive humidity causing equipment corrosion or affecting subsequent reactions. The temperature of the saturated gas needs to be monitored in real time to ensure that it is within the set range, and temperature sensors and automatic control systems need to be used to achieve precise control.

[0029] During the humidification and temperature control process, it is necessary to prevent safety accidents such as gas leakage, fire or explosion. Regularly check the tightness and safety of equipment and pipelines.

[0030] In a further implementation of this embodiment, the saturated coal gas after humidification and temperature control is filtered through a filter to specifically remove impurities toxic to the catalyst in the saturated coal gas after humidification and temperature control to obtain treated saturated coal gas.

[0031] It should be noted that in the aforementioned process of separating saturated coal gas, there will still be some tiny particles and impurities, and water droplets or other liquid particles may be generated during the humidification process.

[0032] Therefore, filtering through the filter can remove tiny particles and impurities in the coal gas, protect the activity and life of the catalyst, ensure the efficient progress of the catalytic reaction, and effectively remove water droplets or other liquid particles that may be produced during the humidification process through the filter to prevent these droplets from affecting subsequent reactions or contaminating products, thereby achieving further cleaning and purification of the saturated coal gas.

[0033] Clean gas can improve the quality and purity of the final product. Removing impurities from saturated gas through filters can prevent these impurities from mixing into the final product and affecting the performance and use of the product.

[0034] Removing impurities from coal gas can ensure the consistency and stability of reaction conditions and improve the selectivity and yield of the reaction.

[0035] Moreover, filtering saturated coal gas through filters can reduce harmful substances emitted into the atmosphere, meet environmental protection requirements, and reduce environmental pollution.

[0036] It should be noted that when using the filter, it is necessary to select the appropriate filtration accuracy according to the process requirements.

[0037] Different filters have different filtration efficiencies. Appropriate filters should be selected based on the size of the particles to be removed. The filter will produce a certain pressure drop during operation, which needs to be monitored and controlled to avoid excessive pressure drop affecting the flow and pressure of the gas. The effect of the temperature and humidity of the gas on the filter performance should also be considered, and filter materials suitable for high temperature or high humidity environments should be selected.

[0038] During the production process, the filter needs to be checked and cleaned regularly, and the filter element or filter bag needs to be replaced when necessary to ensure the normal operation of the filter. When installing and using the filter, pay attention to prevent safety accidents such as gas leakage, fire or explosion. Check the tightness and safety of the filter regularly.

[0039] In a further implementation manner of this embodiment, the waste heat recovery is specifically: the secondary conversion gas is sequentially passed through a boiler feed water heater, a condensate heater and a soft water heater to recover the waste heat.

[0040] It should be noted that the boiler feed water heater preheats the feed water to the required temperature through the secondary conversion gas in a high-temperature state, thereby improving the thermal efficiency and operating economy of the process.

[0041] The secondary conversion gas after heat exchange in the boiler feed water heater is introduced into the condensate heater, and heat is exchanged with the secondary conversion gas through the heat exchange surface in the heater (such as tube bundle or plate heat exchange surface). After absorbing heat, the temperature rises. By adjusting the flow rate or temperature of the secondary conversion gas, the outlet temperature of the condensate can be controlled to reach the required temperature range. The heated condensate can be sent back to the process to form a closed circulation system.

[0042] The secondary conversion gas that has passed through the condenser is further introduced into the soft water heater. The soft water in the heater exchanges heat with the secondary conversion gas through the heat exchange surface (such as tube bundle or plate heat exchange surface) inside the heater. After absorbing heat, the temperature rises. By adjusting the flow rate or power of the secondary conversion gas, the outlet temperature of the soft water can be controlled to reach the required temperature range.

[0043] In a further implementation of this embodiment, a plurality of filters are provided, and the plurality of filters are arranged in parallel or in series, and the number of the filters arranged in the same series route is two.

[0044] It should be noted that by setting two filters on the same series line and allowing the saturated coal gas to pass through the two filters in sequence, the filtering intensity of the saturated coal gas in the process can be further improved to obtain saturated coal gas with high purity and cleanliness.

[0045] By setting up multiple filters in parallel, the working efficiency of the overall process can be effectively improved.

[0046] In a further implementation manner of this embodiment, the condensate in the condensate heater can be recycled to the gasification slag water section for reuse after being treated with gas.

[0047] It should be noted that it not only improves resource utilization, but also reduces wastewater discharge, which is in line with the principle of sustainable development.

[0048] The condensate is collected from the steam system and transported to the condensate heater through a pipeline. The condensate exchanges heat with the heat source (such as high-temperature steam, hot water, etc.) through the heat exchange surface in the heater, and the temperature rises after absorbing heat. The heated condensate is further treated by, for example, a degassing tower, vacuum degassing, chemical treatment, etc. to remove harmful gases or impurities. The condensate after gas treatment can be recycled and transported to the gasification slag water section through a pipeline. The gasification slag water section is usually used to treat the slag water generated during the gasification process. The condensate can be used as supplementary water here to dilute the slag water or participate in other chemical reactions, thereby realizing the reuse of resources.

[0049] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An energy-saving isothermal conversion process, characterized in that: The following steps are involved: The saturated coal gas is treated and introduced into a primary shift isothermal reactor for primary shift reaction to generate primary shift gas; The primary shifted gas is passed through a second steam mixer for heat exchange and then introduced into a secondary shift isothermal reactor for secondary shift reaction to generate secondary shifted gas; Recover waste heat from the secondary conversion gas; The secondary conversion gas after waste heat recovery is further cooled by circulating water and enters the next process.

2. The energy-saving isothermal conversion process according to claim 1, characterized in that: The saturated coal gas is separated from impurities doped in the saturated coal gas by a separator to obtain pre-purified saturated coal gas.

3. The energy-saving isothermal conversion process according to claim 2, characterized in that: The pre-purified saturated coal gas is preheated by the high-temperature shifted gas at the outlet position of the first isothermal converter to obtain preheated saturated coal gas.

4. The energy-saving isothermal conversion process according to claim 3, characterized in that: The preheated saturated coal gas is humidified and temperature-controlled by a first steam mixer to obtain humidified and temperature-controlled saturated coal gas.

5. The energy-saving isothermal conversion process according to claim 4, characterized in that: The saturated coal gas after humidification and temperature control is filtered through a filter to specifically remove impurities toxic to the catalyst in the saturated coal gas after humidification and temperature control to obtain treated saturated coal gas.

6. The energy-saving isothermal conversion process according to claim 5, characterized in that: The waste heat recovery is specifically as follows: the secondary conversion gas is sequentially passed through a boiler feed water heater, a condensate heater and a soft water heater to recover the waste heat.

7. The energy-saving isothermal conversion process according to claim 5, characterized in that: There are multiple filters, and the multiple filters are arranged in parallel or in series, and the number of filters arranged in the same series route is two.

8. The energy-saving isothermal conversion process according to claim 6, characterized in that: The condensate in the condensate heater can be recycled and reused in the gasification slag water section after being treated with gas.