【JST-001】One-on-one Q&A on control instrument design 【Technology updated to Floor 66】
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This post was last edited by Wang Tianze on 2015-4-18 at 20:09. My strengths include design and procurement in petrochemical process automation (instrumentation). Work experience: 7 years of experience in petrochemical design institutes, 3 years of experience in instrument procurement. Rich experience in design, procurement, on-site work, and EPC. This year, we have more time, so I’d like to use this post to exchange ideas and learn together. I will answer every question raised by Haiyou! If there are any questions that I am unable to answer due to limited knowledge and experience, I will provide responses through other channels. In short, the purpose is first to help Haiyou resolve their doubts and provide them with relevant materials, and second to discuss together in order to improve learning. Note: 1) The content is unrestricted. 2) This post welcomes fellow netizens to join the discussion!
I wonder if the original poster has any experience in selecting gas main pipes. Generally, traditional orifice plates are preferred for this purpose, but these days ultrasonic methods are often used as well. I’d like to hear if the original poster has any experience or insights on this topic
The silver insulation layer in the image covers the copper tubes – what is its purpose? Is it for bypassing?
Flow measurement of the main gas pipeline is a common application, and for such cases, basically three types of instruments are used for measurement. Ba class, Thermo mass, ultrasound. I’m not sure which type of gas you’re referring to; common ones include coke oven gas, blast furnace gas, and mixed gases. Firstly, orifice plates are not recommended. Gas main pipes are generally large in diameter, have low flow rates and low pressures, and often contain substances with high viscosity such as oil and naphthalene. Additionally, blast furnace gas may contain water or impurities, which can easily clog the pressure-taking holes, making it difficult to select appropriate differential pressure transmitters. Barometric flow meters should work, but due to the extremely low pressure difference – the actual measurement might be only in the range of a few dozen Pascals – their performance in practical applications is not very good. The ultrasonic pressure loss is almost 0, making it particularly suitable for large pipe diameters; it is convenient and cost-effective, and involves non-contact measurement, so I think it is worth considering. If we are to use one, I recommend thermal mass flow meters; there are application cases available and their performance is good. I hope this can help you.
Please provide detailed information on the operating conditions, medium, temperature, pressure, and location.
Only that it is soybean oil; other details are unknown
May I ask the original poster: if a chemical project adopts the MIV model, are there any successful cases of instrument manufacturers in China? I’ve seen many online reviews stating that contracts are signed with foreign companies such as Emerson, ABB, and Henghe Electromechanical. I would like to ask what are the differences between foreign companies and domestic companies when engaging in MIV, what are their respective advantages and disadvantages, and what points need to be taken into consideration? Thank you.
This… might be jacketed heating. It seems I can’t help you.
That’s quite sharp; it hits right at our pain points again. At present, for large-scale engineering projects, it is still common for the engineering company to play the leading role in EPC, with automation solution providers acting as MAV (Primary Automation Vendor) and MIV (Primary Instrumentation Contractor). In China, as far as I know, it’s pretty unlikely; I haven’t heard much about it. The reason is simple: they fail to master the core technologies, or do not have the capability to dominate both upstream and downstream sectors. In other words, it should not only be a manufacturer of DCS and instruments, but also possess engineering experience in the construction of chemical plants; it should combine the roles of manufacturer, integrator, and engineering company. Whether considered in terms of national conditions, market division of labor, or technical capabilities, it is estimated to be immature. Foreign giants have comprehensive product lines and proven engineering experience, enabling them to provide fully automated solutions. In the domestic market, the only option is to carry out combined acquisitions in order to create a complete product chain; this is the trend for the future. Currently, Zhongkong is also working on this – it has its own DCS system, developed its own bus technologies, as well as its own field instruments. However, it is difficult to promote these products. In short, the gap is still quite noticeable.
This post was last edited by Sichuan Instrument Control Novice on 2015-1-23 22:08. Well, our top bosses want to go ahead with this, and there are basically two reasons for that: they want to pay less, and they also want the payment to be made over a longer period of time – after all, having large amounts of debt in hand gives them power. Personally, I would prefer to work for large companies like Emerson, but the management wants to keep costs low. So are you sure about what the evaluation criteria are for MIV and MAV, and what the scores for each one are? When you work on MIVs and MAVs, do you pack materials such as cables and cable trays together as well? How is the interface for purchasing generally structured? If it is a product that neither MIV nor MAV has, is it purchased separately by the EPC party or the owner? Additionally, could you provide a template for the framework agreements for MIV and MAV that you have signed, or explain the criteria and methods used by you to determine MIV and MAV?
I’ve seen that Emerson and others usually go for large-scale projects when signing contracts; so I wonder, if the total budget for MIV and MAV is limited (around 1 KW), would giants like Emerson turn down such projects?