The realistic first step toward reducing a plant’s CO2 in pursuit of carbon neutrality is to stop sending steam at its generation pressure and instead reduce it to the pressure each piece of equipment actually needs, using it without excess or shortfall. Because steam is produced by burning fuel in a boiler, optimizing how steam is used translates directly into reduced fuel consumption and, in turn, lower CO2 emissions. Before undertaking a large-scale equipment overhaul, there is often considerable room for improvement in existing steam lines. Here, we organize how to get started around the use of valves, following the order of practical work.
Key points of this article
- Steam energy savings lead directly to reduced boiler fuel, which means reduced CO2, so reviewing steam lines is a decarbonization measure that is easy to begin.
- The starting point is to inspect three items: reducing to the appropriate pressure, suppressing leakage and heat radiation, and sizing bore diameters to match the actual flow rate.
- A single valve will not produce a dramatic reduction; results tend to come from accumulating multiple small improvements.
Why reviewing steam leads to CO2 reduction
Steam is produced by heating water in a boiler, and that heat source is in many cases fuel such as gas or heavy oil. In other words, the more steam is wasted, the more extra fuel is burned and the more CO2 is emitted. Conversely, the closer the operation comes to delivering only the amount of heat that is needed, the easier it is to curb both fuel and emissions.
An easily overlooked issue is supplying steam at excessive pressure. When steam is sent to end-use equipment at the boiler’s generation pressure, the amount exceeding the pressure the equipment requires tends to be lost as excess steam consumption or heat radiation. Adjusting the pressure to the level each piece of equipment needs with a pressure reducing valve is one of the basic measures to consider first in a steam line.
Three perspectives to inspect first
The following three points are worth keeping in mind as a way to get started. First, whether the supply pressure is excessive relative to the pressure each piece of equipment requires. Second, whether there is steam leakage from connections or glands, or heat radiation due to insufficient insulation. Third, whether the bore diameters of valves and piping are too large or too small relative to the actual flow rate. All of these are items you can begin by grasping the current situation without any special capital investment, making them an area that is easy to tackle as a first step toward decarbonization.
How to get started, centered on the pressure reducing valve
As a concrete point of entry, achieving appropriate pressure with a pressure reducing valve is an easy-to-understand starting point. Lowering excessive pressure to the required pressure tends to reduce overconsumption of steam and heat radiation, and it also contributes to stabilizing the temperature and pressure on the equipment side. However, because the effect varies greatly with pressure conditions, flow rate, and operation, the amount of reduction cannot be guaranteed by a uniform figure; it must be projected in light of the conditions of your own line.
Think of the effect as an accumulation
CO2 reduction is not determined by a single valve; it is the accumulation of multiple factors. In addition to achieving appropriate pressure through reduction, layering measures such as repairing leaks, adding insulation, and reviewing bore diameters to match the actual flow rate makes it easier to curb overall fuel consumption. A reasonable way to begin is to first make the actual state of pressure, flow rate, and leakage visible, then address the highest-priority points in order.
Frequently asked questions
Q1. How much CO2 reduction do steam energy savings achieve?
A1. Because the effect varies greatly with pressure, flow rate, and operation, no uniform figure can be given. Please understand it in terms of the idea that reducing steam consumption leads to reduced fuel and, as a result, contributes to curbing CO2.
Q2. Where should I start?
A2. In general, checking whether the supply pressure is excessive relative to the pressure each piece of equipment requires is an easy-to-approach guideline. Together with this, inspect leakage, insulation, and the appropriateness of bore diameters.
Q3. Won’t results come only if I carry out a major equipment overhaul?
A3. Not necessarily. There are often opportunities to start with limited investment on existing lines, such as achieving appropriate pressure or suppressing leakage and heat radiation.
Q4. Will installing a pressure reducing valve always save energy?
A4. Lowering excessive pressure is itself a valid direction, but the effect depends on the conditions. Excessive reduction or an inappropriate bore diameter can fail to produce an effect, so selection matched to the actual conditions is a prerequisite.
Q5. How can I grasp the effect?
A5. A useful guideline is to compare actual measurements of steam flow rate and fuel consumption before and after the measure. When visualization is difficult, the reliable approach is to organize the conditions and make use of a technical consultation.
Q6. Can existing steam lines also be reviewed?
A6. In many cases they can. Flow rate, pressure, and operation may have changed between the time of installation and now, so reconfirming the conditions at the occasion of an update or improvement increases accuracy.
Summary
Reducing a plant’s CO2 can begin by moving toward an operation that uses steam at the necessary pressure and flow rate, without excess or shortfall. Starting from achieving appropriate pressure with a pressure reducing valve, and layering the suppression of leakage and heat radiation and the review of bore diameters to match the actual flow rate, is a realistic path toward reduced fuel, meaning curbed CO2. In every case, starting from a guideline and applying it to your own actual data is what determines the result.
If you have concerns such as “I can’t judge whether the supply pressure is excessive,” “I know the maximum flow rate but not the minimum flow rate, so I can’t select a pressure reducing valve,” or “I want to select an equivalent for an existing valve, but the operation has changed,” please organize your conditions and make use of Yoshitake’s technical and selection consultations. Based on your application and pressure and flow rate conditions, we will consider valve use that leads to decarbonization together with you.